[Feature Request] - Custom Template for Labeling Interface

**Is your feature request related to a problem? Please describe.**
Hey, this projects is really great and me and my team use it almost everyday. But, each time when creating a projects, I need to copy/paste the labelling interface.

**Describe the solution you'd like**
What I had in mind are that the custom template that I already made is listed in this page. You can say that I have custom xml is saved somewhere in the label studio database.

**Describe alternatives you've considered**
I just copy my xml code from previous projects when creating a new projects. Doable, but it's great improvement of quality of life if we have feature like I described above

Cheers,