Generate and handle a gl_repository param to pass around components

What does this MR do?

Generate an handle a gl_repository param to pass around components

This new param allows us to share project information between components that don't share or don't have access to the same filesystem mountpoints, for example between Gitaly and Rails or between Rails and Gitlab-Shell hooks. The previous parameters are still supported, but if found, gl_repository is prefered. The old parameters should be deprecated once all components support the new format.

Are there points in the code the reviewer needs to double check?

Do we need to document this (other than comments in the code)?

Why was this MR needed?

GitLab components shouldn't pass absolute paths between each other, because we're planning for them to be able to be distributed amongst different hosts with different filesystem mounts.

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #29925 (closed)