Resolve "Redirect to new project link after a rename"

What does this MR do?

When the path of a routable object (Group, Namespace, Project) is changed, a redirect is created from the old path to the new. This also applies to route descendants, e.g. renaming a group affects the paths of subgroups and projects.

Furthermore, new or updated routes override redirects with conflicting paths.

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

See !10370 (closed) for full work. This branch was created to avoid Job timeouts.

Why was this MR needed?

Renaming groups and projects is a valuable feature, but the user is forced to accept that they are breaking links. This redirect behavior will make renaming less impactful (in a good way). See #17361 (closed).

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 #17361 (closed)

Closes #30317 (closed)