Enable several git instances in profile, and enable git profiles selection in services

Hi,

It would be useful and great to enable different git profiles in Onyxia, so in my service I enable either a specific account, or several (what do you think of this second option ?).

Indeed, sometime my work gets from github, sometimes from gitlab, sometimes it can come from elsewhere (BitBucket, sourceforge, ...).

For exemple in the profile:

And then in the service, enable to chose between 0 and several git credentials.

Thanks for considering, keep up the god work !