Channel group loading refactor

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.
• I have read and understood the AI policy. The content of this request is not generated by AI.

Feature description

This proposal breaks rule of one proposal per issue but it is more like design proposal for rewrite so...

Currently there is 1 global Immutable queue for feed subscriptions update which also blocks you to view what is in channel group. Not sure it is immutable in code but at least for user it is effectively immutable

So what I propose:

1. Make feed update queue mutable (if it is not)
2. When you open channel group and it contains subscriptions from the queue, if intersection is empty show channel group right away.
3. When you open channel group and it contains subscriptions from the queue, you show channel group right away when last subscription of channel group is loaded
4. When you open channel group and it contains subscriptions from the queue, rebuild queue so subscriptions from the channel group are scheduled first

Why do you want this feature?

You have some subscriptions organized in channel groups. You open one channel group and press update. It starts updating subscriptions of that specific channel group. You exit from the group and go to another one and you can't see videos because you need to wait till the feed will finish update (Even if the channel groups doesn't intersect).

Example which is more near to real life. I open app. Go to all channel group, press update, exit and go to specific channel group I am interested in. I need to wait till all the subscriptions will be updated (while it could happen in background)

UX. I have now ~35 subscriptions and it is already slow but I plan to add all my other subscriptions so it will be 90 and it will be really slow

Additional information

No response