Add routes to allow git actions on snippet repositories

What does this MR do?

In this MR we implement the following:

• Refactors the git_http routes because, for now, snippet repositories won't support LFS (mainly because lfs_enabled is a project feature and we have to think if we could enable it by default for personal snippets).
• It also updates the GitHttpController(s) and the SSH internal API to allow basic cloning/pushing/pulling operations for resources other than projects.

Refs #39176 (closed) Closes #205666 (closed)

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Separation of EE specific content

app/controllers/namespaces/git_http_controller.rb

@@ -82,10 +82,12 @@ def enqueue_fetch_statistics_update
   end
 
   def access
-    @access ||= access_klass.new(access_actor, @subject,
-      'http', authentication_abilities: authentication_abilities,
-      namespace_path: params[:namespace_id], project_path: project_path,
-      redirected_path: redirected_path, auth_result_type: auth_result_type)
+    @access ||= access_klass.new(access_actor, @subject, 'http',
+      authentication_abilities: authentication_abilities,
+      namespace_path: params[:namespace_id],
+      project_path: project_path,
+      redirected_path: redirected_path,
+      auth_result_type: auth_result_type)
   end
 
   def access_actor