Add option to import/clone repo from internal project on same Gitlab instance

Description

It seems like there's no easy and nice solution to import/clone a repo from another internal project on the same Gitlab instance when creating a new project.

I finally managed to import internal git repos using the following import_url format:

ssh://git.example.org/var/opt/gitlab/git-data/repositories/group/project.git

But to be honest, that is a bit clunky and not very user-friendly.

Proposal

I suggest to add a new import from internal project function.

Additionally, the 'git://user@git.example.org:group/project.git' format should be supported. Apparently it's not right now. The colon (':') causes Gitlab to throw an error.