Notify the user that their fork is out of date ( and therefore has old translations/translations are not setup)

[DrRuhe]

I had an old fork of appflowy lying around and so when opening inlang on the main appflowy repo it prompted me to create a fork (it should probably detect existing forks?) and after clicking I was greeted with an error message that the /project.inlang.json file was missing.

The reason was it simply used the old existing fork which was like 400 commits behind main, so the /project.inlang.json file was not yet setup. This was confusing and not obvious to me. Luckily I found the reason quickly, but this almost drove me away from contributing using inlang.

So all in all, warn the user if their fork is outdated, (I imagine this would also prevent users from translating keys already translated in the main branch). And especially tell the user their fork is not setup properly, but the upstream version is, so the user should consider syncing their fork.

[samuelstroschein]

Thanks for the feedback!

The forking logic is complicated. @inlang/lix can we improve the forking logic to inform inlang apps to prompt "this fork is outdated"?