Introduce cache policies for CI jobs

What does this MR do?

Allows jobs to ask for cache uploads or downloads to be skipped, independently of each other. This allows jobs that don't rely on the cache to just perform uploads, or jobs that don't change the cache to just perform downloads.

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

GitLab Runner support in https://gitlab.com/gitlab-org/gitlab-ci-multi-runner/merge_requests/621

Why was this MR needed?

Screenshots (if relevant)

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 #33772 (closed)