TeamPiped channel groups compatibility

[foxjaw]

Checklist

• I made sure that there are no existing issues - open or closed - which I could contribute my information to.
• I have read the FAQ and my problem isn't listed.
• I'm aware that this is a request for NewPipe itself and that requests for adding a new service need to be made at NewPipeExtractor.
• I have taken the time to fill in all the required details. I understand that the feature request will be dismissed otherwise.
• This issue contains only one feature request.
• I have read and understood the contribution guidelines.

Feature description

Piped instances support channel groups too. But unfortunately can't import and export channel groups between these two.

Why do you want this feature?

To import and export not just subscriptions, but also channel groups with it, so that both Piped website and newpipe app share the same databases.

Additional information

TeamPiped/Piped#3566

[opusforlife2]

Also see UniversalPipeWrench/unified-user-data-format#1.