[Android] Own Notification Channel for the desktop library notification

As some of you may know the Desktop Android Dev Team introduced at some point Notification Channels (API level 26). I'm using them to deactivate the casting of specific push notifications—that is, in my opinion, a better option as to deactivate all notification. You know that if you install a game on the desktop from your library, that you'll receive a push notification on your Android device, that's fine but sadly it puts them below the Notification channel 'Friends' and not below an own channel, therefore it would be neat if it would get separated from 'Friends'