Add new field mediaType to ContainerRegistry::Tag

Epic: Improve container registry multi-architecture i... (&11952)

In #411387 (closed), we integrated the new list repository tags API from the container registry.

The endpoint GET /gitlab/v1/repositories/<path>/tags/list/ (docs) returns the media_type field, so this field needs to be integrated into rails

Adding mediaType field will unblock Display icon/badge alongside container registry... (#408865 - closed) & Do not show (zero) size of container registry m... (#431048 - closed)

Implementation plan

With this issue, we want to:

  1. Add a new attribute media_type to ContainerRegistry::Tag
  2. Fill up this new attribute from the API endpoint (if Gitlab.com)
  3. Set to nil? (if not Gitlab.com)
  4. Add new field media_type to ContainerRepositoryTagType so it can be accessible via the Rails API.
  5. Ensure that mediaType is part of the GraphQL endpoint.
Edited by Rahul Chanila