Mark videos as watched in all places

[nschulzke]

Checklist

• I checked, but didn't find any duplicates (open OR closed) of this issue in the repo.
• I have read the contribution guidelines given at https://github.com/TeamNewPipe/NewPipe/blob/HEAD/.github/CONTRIBUTING.md.
• This issue contains only one feature request. I will open one issue for every feature I want to request.

Describe the feature you want

We recently implemented the ability to mark a video as watched, but this option is only visible from the subscriptions view. We want to make it work from any feed.

Is your feature request related to a problem? Please describe it

I would like to be able to mark videos as watched in a playlist, for example.

Additional context

This was actually originally suggested by @Pentaphon here: #6773 (comment)

I intend to implement this shortly.

How will you/everyone benefit from this feature?

We'll be able to mark videos as watched without being subscribed to their feed.