WIP: Checks if user already owns a project with that name and hides the Edit button if true

The final idea is that if the project already owns a project with that name we try to fetch the branches of the other user's fork and apply changes to it instead of trying to fork the project and failing

This MR aims to fix issue #19926 (moved)

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