Get recipe files with revision

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What does this MR do and why?

This MR adds the conan V2 endpoint to get the recipe files from a package that is also used by V1 with revisions.

References

• #519741 (closed)
• #333033 (closed)
• !181393 (merged)

How to set up and validate locally

1. Switch the conan_package_revisions_support feature flag on.

   For GDK, open rails console (docs):

   gdk rails console

   Enable the feature flag:

   # Enable
   Feature.enable(:conan_package_revisions_support)
   
   # Verify
   Feature.enabled?(:conan_package_revisions_support)

2. Get Conan Authentication Token

   First, generate a base64-encoded Basic Auth token:

   # Replace with your username and PAT
   echo -n "USERNAME:glpat-YOUR-TOKEN"|base64

   Then use the output to get a Conan JWT token:

   curl --request GET \
   --url 'http://localhost:3000/api/v4/projects/<project_id>/packages/conan/v1/users/authenticate' \
   --header 'Authorization: Basic <YOUR-BASE64-TOKEN>'

3. Make sure there are two recipe files uploaded.

   You will have to check out the 333033-put-endpoint-revision-recipe-file branch to be able to upload recipe files as a prerequisite for manual testing. Follow the instructions here to manually upload 2 recipe files (conanfile.py and conanmanifest.txt).

4. Call the get recipe files endpoint

   Make sure you are back on this branch 333033-get-recipe-files-with-revision and run:

   curl --request GET \
   'http://localhost:3000/api/v4/projects/<project_id>/packages/conan/v2/conans/upload-v2-package/1.0.0/user/stable/revisions/123456789012345678901234567890ab/files' \
   --header 'Authorization: Bearer <YOUR-CONAN-JWT-TOKEN>'

   that should return status 200 OK and body:

   {"files":{"conanfile.py":{},"conanmanifest.txt":{}}}

/cc @oceane_scania

Related to #333033 (closed)