Before the we would try to `POST` to the project path, which would
result in a 404, because that `POST` is not supported.
By changing this back to a normal link, not not handled in JS, we can
immeadiatly redirect.
Previously the fork button was disabled for all users if they have
exceeded their project limit. This fixes that by changing the check
to see if the user can fork to a group instead of their own namespace.
This behaviour is already possible by visiting the new fork page
directly, so this just fixes the button being disabled.
Closes#38462
Stan Hu