Add "project moved" error messages to git

What does this MR do?

Adds helpful error messages to git rejections when you push/pull a project that was moved. This is a direct follow-on to !10370 (closed).

Tasks

• Test git actions locally
• https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/10370#note_28858283
• https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/10370#note_28858492
• https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/10370#note_28858546

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

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?

#17361 (closed)