Support Gitea in addition to Github

[morki]

We must use custom Gitea instance for development, it would be awesome to be able to use Junie in it.

[sweethuman]

I wish in general more software support Gitea and other git hosts besides Github and Gitlab, Gitea even has similar API to Github.

Github isn't improving because it has a hold on the industry, network effect, everything works with Github the best... better use Github. We as a company used to use JetBrains SpaceCode before they shut it down... IT WAS THE BEST pure Git + PR experience, did one thing and did it amazingly. Now we're on Github (migrated quickly to something) and I'm looking at other options for us... but it's too much pain to move anywhere... or pay the big toll of Gitlab for a bunch of features we will never use...