[Feature] Unified Push support

[SadmL]

Website
https://unifiedpush.org

Clients that already supports UnifiedPush
https://github.com/Mercurygram/Mercurygram
https://github.com/forkgram/TelegramAndroid

[Sahibishere]

Can we also allow it for other unfied distributors such as cheogram which require unified connecter version 3.x and up?