Add basic components to display dep proxy manifests

What does this MR do and why?

This MR adds:

• the two components necessary to implement the manifests list
• the necessary query changes to the main query

For the sake of MR size the new components are not connected to the main app, so this MR actually provides zero changes to the UI

Screenshots or screen recordings

No visual changes

How to set up and validate locally

1. Apply this patch: AttachManifestList.patch
2. Login into rails console: rails c
3. FactoryBot.create(:dependency_proxy_manifest, group: Group.first)
4. Repeat the above a few times
5. Go to the first group in your GDK (usually gitlab-org) depdendency proxy

Note that the console may complain on missing fixture_file_upload in that case add this to the console and try again

def fixture_file_upload(*args, **kwargs)
  Rack::Test::UploadedFile.new(*args, **kwargs)
end

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #250865 (closed)