feat(gui): localization package source

[lonelyicer]

[anatawa12]

Thank you for suggestion

I think this should be implemented after #628 and we have to consider if we should inject into VRChat official repository or not since it's close to modifying the repository so unfortunately I don't merge for now.

For future me: if we choose to inject into vrchat official repository, I think we should detect repository by repository id instead of name.