Notification channel groups as data parameter

**Is your feature request related to a problem? Please describe.**

There's an unused option to group notification channels on Android. This is a promising feature to categorize and configure tens to hundreds of different notification channels with similar names.

**Describe the solution you'd like**

Add an optional `channel_group` data attribute that would be parsed before the `createNotificationChannel` phase (in the `notificationManager.createNotificationChannelGroup` call).

**Describe alternatives you've considered, if any**

– Using Telegram notifications (not actionable enough)
– Merging notification channels (I don't need notifications for some channels occasionally, and renaming them becomes a mess)
– Modifying scripts to not send notifications (not portable)

**Additional context**

Implementation in question: https://developer.android.com/develop/ui/views/notifications/channels#CreateChannelGroup

Presumed place to inject code: https://github.com/home-assistant/android/blob/master/common%2Fsrc%2Fmain%2Fkotlin%2Fio%2Fhomeassistant%2Fcompanion%2Fandroid%2Fcommon%2Fnotifications%2FNotificationFunctions.kt#L99