support gitlab org/project/group variables

[teto]

in my organization, we started switching to novops to ease the reproduction of gitlab jobs locally.
It's huge work though so having the ability to fetch variables from gitlab could ease the transition. Furthermore some variables are global to the organization and might make sense to fetch from gitlab rather than copy/paste across all .novops.yml files.

[PierreBeucher]

Ah yes definitely a must have