Let user filter out watched videos in ChannelFragment

[BURG3R5]

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 Tubular itself and that requests for adding a new service need to be made in vanilla 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 vanilla NewPipe contribution guidelines.
• I have read and understood the AI policy. The content of this request is not generated by AI.

Feature description

FeedFragment provides the option to hide upcoming and fully-/partially-watched videos. I would like a similar dialog in ChannelFragment. This will de-clutter the feed as well as make both feeds consistent.

Probably should have separate (but global) pref keys for the channel feed (for example, add a new channel_feed_show_partially_watched_items_key instead of reusing feed_show_partially_watched_items_key).

Why do you want this feature?

Discovering old/unwatched videos from a channel currently requires scrolling for miles.

Why is the feature relevant to this fork?

Upstream is not accepting new features in the current stable version.

Additional information

I'd be happy to develop this feature, if it's green-lit.

Edit: After reviewing the codebase (especially the differences between the two fragments)... I will probably need some guidance.

[dftf-stu]

@polymorphicshade : not sure where this request would stand?

It's clearly not something that is specific to Tubular (such as the SponsorBlock or Restore YouTube Dislikes extras), but is being logged here because "[NewPipe] is not accepting new features in the current stable version".

So what's the policy here, now, during NewPipe's transition to their new codebase and UI?

1. Wait until the new version of NewPipe releases, then log it with them
2. Accept requests here in the meantime for stuff that previously would be rejected, as it isn't Tubular-specific?