Add License Management API to the backend

What does this MR do?

It adds approval and blacklist API for software licenses; see https://gitlab.com/gitlab-org/gitlab-ee/issues/5488

Why was this MR needed?

To implement https://gitlab.com/gitlab-org/gitlab-ee/issues/5488

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Conform by the code review guidelines
  • Has been reviewed by a UX Designer
  • Has been reviewed by a Frontend maintainer
  • Has been reviewed by a Backend maintainer
  • Has been reviewed by a Database specialist
• EE specific content should be in the top level /ee folder
• Conform by the merge request performance guides
• Conform by the style guides
• If you have multiple commits, please combine them into a few logically organized commits by squashing them
• Internationalization required/considered
• If paid feature, have we considered GitLab.com plan and how it works for groups and is there a design for promoting it to users who aren't on the correct plan
• End-to-end tests pass (package-and-qa manual pipeline job)

What are the relevant issue numbers?

Refs #5488 (closed)

ee/spec/controllers/projects/managed_licenses_controller_spec.rb

 require 'spec_helper'
 
 describe Projects::ManagedLicensesController do
-  let(:project) { create(:project) }
-  let(:maintainer_user) { create(:user) }
-  let(:dev_user) { create(:user) }
+  let(:project) do
+    create(:project).tap do |p|
+      @software_license_policy = create(:software_license_policy, project: p)
+    end
+  end
+
+  let(:maintainer_user) do
+    create(:user).tap do |u|
+      project.add_maintainer(u)
+    end
+  end
+
+  let(:dev_user) do
+    create(:user).tap do |u|
+      project.add_developer(u)
+    end
+  end
+
+  let(:reporter_user) do
+    create(:user).tap do |u|
+      create(:project_member, :reporter, user: u, project: project)
+    end
+  end
+
   let(:other_user) { create(:user) }
-  let(:unsigned_user) { create(:user) }
 
-  before do
-    project.add_maintainer(maintainer_user)
-    project.add_developer(dev_user)
+  let(:unlogged_user) { nil }
+
+  let(:software_license_policy) do
+    @software_license_policy ||= create(:software_license_policy, project: project)
   end
 
-  describe 'GET #index' do
-    let!(:software_license_policy) { create(:software_license_policy, project: project) }
+  before { stub_licensed_features(license_management: true) }
 
+  describe 'GET #index' do
     subject do
       allow(controller).to receive(:current_user).and_return(user)
 
@@ -32,12 +53,12 @@
     end
 
     context 'with no logged in user' do
-      let(:user) { unsigned_user }
+      let(:user) { unlogged_user }
 
-      it 'returns a 404 error code' do
+      it 'returns a 401 error code' do
         subject
 
-        expect(response).to have_gitlab_http_status(:not_found)
+        expect(response).to have_gitlab_http_status(:unauthorized)
       end
     end
 
@@ -59,8 +80,6 @@
   end
 
   describe 'GET #show' do
-    let!(:software_license_policy) { create(:software_license_policy, project: project) }
-
     subject do
       allow(controller).to receive(:current_user).and_return(user)
 
@@ -82,12 +101,12 @@
     end
 
     context 'with no logged in user' do
-      let(:user) { unsigned_user }
+      let(:user) { unlogged_user }
 
-      it 'returns a 404 error code' do
+      it 'returns a 401 error code' do
         subject
 
-        expect(response).to have_gitlab_http_status(:not_found)
+        expect(response).to have_gitlab_http_status(:unauthorized)
       end
     end
 
@@ -110,7 +129,6 @@
   end
 
   describe 'GET #show with license name as identifier' do
-    let!(:software_license_policy) { create(:software_license_policy, project: project) }
     let(:user) { dev_user }
 
     subject do
@@ -138,9 +156,6 @@
   end
 
   describe 'POST #create' do
-    let!(:software_license_policy) { create(:software_license_policy, project: project) }
-    let(:owner) { project }
-
     let(:software_license_policy_attributes) do
       { id: software_license_policy.id,
         name: software_license_policy.name,
@@ -170,7 +185,7 @@
       end
 
       it 'returns a 403 error code' do
-        expect { subject }.not_to change { owner.software_license_policies.count }
+        expect { subject }.not_to change { project.software_license_policies.count }
 
         expect(response).to have_gitlab_http_status(:forbidden)
       end
@@ -184,23 +199,23 @@
       end
 
       it 'returns a 404 error code' do
-        expect { subject }.not_to change { owner.software_license_policies.count }
+        expect { subject }.not_to change { project.software_license_policies.count }
 
         expect(response).to have_gitlab_http_status(:not_found)
       end
     end
 
     context 'with no logged in user' do
-      let(:user) { unsigned_user }
+      let(:user) { unlogged_user }
 
       let(:to_create_software_license_policy_attributes) do
         new_software_license_policy_attributes
       end
 
-      it 'returns a 404 error code' do
-        expect { subject }.not_to change { owner.software_license_policies.count }
+      it 'returns a 401 error code' do
+        expect { subject }.not_to change { project.software_license_policies.count }
 
-        expect(response).to have_gitlab_http_status(:not_found)
+        expect(response).to have_gitlab_http_status(:unauthorized)
       end
     end
 
@@ -217,7 +232,7 @@
         end
 
         it 'does not create the new software license policy' do
-          expect { subject }.not_to change { owner.software_license_policies.count }
+          expect { subject }.not_to change { project.software_license_policies.count }
         end
 
         it 'returns a bad request response' do
@@ -233,7 +248,7 @@
         end
 
         it 'creates the new software license policy' do
-          expect { subject }.to change { owner.software_license_policies.count }.by(1)
+          expect { subject }.to change { project.software_license_policies.count }.by(1)
         end
 
         it 'returns a 200 response' do
@@ -246,9 +261,6 @@
   end
 
   describe 'PATCH #update' do
-    let!(:software_license_policy) { create(:software_license_policy, project: project) }
-    let(:owner) { project }
-
     let(:software_license_policy_attributes) do
       { id: software_license_policy.id,
         name: software_license_policy.name,
@@ -283,7 +295,7 @@
       end
 
       it 'returns a 403 error code' do
-        expect { subject }.not_to change { owner.software_license_policies.count }
+        expect { subject }.not_to change { project.software_license_policies.count }
 
         expect(response).to have_gitlab_http_status(:forbidden)
       end
@@ -297,23 +309,23 @@
       end
 
       it 'returns a 404 error code' do
-        expect { subject }.not_to change { owner.software_license_policies.count }
+        expect { subject }.not_to change { project.software_license_policies.count }
 
         expect(response).to have_gitlab_http_status(:not_found)
       end
     end
 
     context 'with no logged in user' do
-      let(:user) { unsigned_user }
+      let(:user) { unlogged_user }
 
       let(:to_create_software_license_policy_attributes) do
         new_software_license_policy_attributes
       end
 
-      it 'returns a 404 error code' do
-        expect { subject }.not_to change { owner.software_license_policies.count }
+      it 'returns a 401 error code' do
+        expect { subject }.not_to change { project.software_license_policies.count }
 
-        expect(response).to have_gitlab_http_status(:not_found)
+        expect(response).to have_gitlab_http_status(:unauthorized)
       end
     end
 
@@ -330,7 +342,7 @@
         end
 
         it 'does not create the new software license policy' do
-          expect { subject }.not_to change { owner.software_license_policies.count }
+          expect { subject }.not_to change { project.software_license_policies.count }
         end
 
         it 'returns a bad request response' do
@@ -346,7 +358,7 @@
         end
 
         it 'does not create a new software license policy' do
-          expect { subject }.not_to change { owner.software_license_policies.count }
+          expect { subject }.not_to change { project.software_license_policies.count }
         end
 
         it 'returns a successful response' do
@@ -366,8 +378,6 @@
   end
 
   describe 'DELETE #destroy' do
-    let!(:software_license_policy) { create(:software_license_policy, project: project) }
-    let(:owner) { project }
     let(:id_to_destroy) { software_license_policy.id }
 
     subject do
@@ -388,7 +398,7 @@
       end
 
       it 'returns a 403 error code' do
-        expect { subject }.not_to change { owner.software_license_policies.count }
+        expect { subject }.not_to change { project.software_license_policies.count }
 
         expect(response).to have_gitlab_http_status(:forbidden)
       end
@@ -402,23 +412,23 @@
       end
 
       it 'returns a 404 error code' do
-        expect { subject }.not_to change { owner.software_license_policies.count }
+        expect { subject }.not_to change { project.software_license_policies.count }
 
         expect(response).to have_gitlab_http_status(:not_found)
       end
     end
 
     context 'with no logged in user' do
-      let(:user) { unsigned_user }
+      let(:user) { unlogged_user }
 
       let(:to_create_software_license_policy_attributes) do
         new_software_license_policy_attributes
       end
 
-      it 'returns a 404 error code' do
-        expect { subject }.not_to change { owner.software_license_policies.count }
+      it 'returns a 401 error code' do
+        expect { subject }.not_to change { project.software_license_policies.count }
 
-        expect(response).to have_gitlab_http_status(:not_found)
+        expect(response).to have_gitlab_http_status(:unauthorized)
       end
     end
 
@@ -427,7 +437,7 @@
 
       context 'with an existing software license policy' do
         it 'destroys the software license policy' do
-          expect { subject }.to change { owner.software_license_policies.count }.by(-1)
+          expect { subject }.to change { project.software_license_policies.count }.by(-1)
           expect { software_license_policy.reload }.to raise_error ActiveRecord::RecordNotFound
         end
 
@@ -448,7 +458,7 @@
         let(:id_to_destroy) { 12341234 }
 
         it 'does not destroy any software license policy' do
-          expect { subject }.to change { owner.software_license_policies.count }.by(0)
+          expect { subject }.to change { project.software_license_policies.count }.by(0)
           expect { software_license_policy.reload }.not_to raise_error
         end