Resolve "Send deployment information in job API"

What does this MR do?

Extend BuildDetailEnity to include a new key deployment_status which has all the information about deployments.

What are the relevant issue numbers?

gitlab-org/gitlab-ce#50460

gitlab-org/gitlab-ce#50101

To Do

• Create issue for environment json schema

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• Tests added for this feature/bug
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides

Closes #50460 (closed)

app/models/ci/build.rb

@@ -654,8 +654,31 @@ def collect_test_reports!(test_reports)
       end
     end
 
+    # Virtual deployment status depending on the environment status.
+    def deployment_status
+      return nil unless starts_environment?
+
+      if success?
+        return successful_deployment_status
+      elsif complete? && !success?
+        return :failed
+      end
+
+      :creating
+    end
+
     private
 
+    def successful_deployment_status
+      if success? && last_deployment&.last?
+        return :last
+      elsif success? && last_deployment.present?
+        return :out_of_date
+      end
+
+      :creating
+    end
+
     def each_test_report
       Ci::JobArtifact::TEST_REPORT_FILE_TYPES.each do |file_type|
         public_send("job_artifacts_#{file_type}").each_blob do |blob| # rubocop:disable GitlabSecurity/PublicSend