Add channel to group without subscribing

[rsapkf]

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

Please allow adding channels to groups without having to subscribe.

Why do you want this feature?

I want to make a group of channels to keep a watch on without necessarily committing to subscribing and "polluting" my main feed.

Additional information

No response

[opusforlife2]

Alternative: #3319.

[SameenAhnaf]

I'd rather recommend remembering actions like Group A-Group B or All-Group B as mentioned in #5615