Show if video is (already) added to playlist

[dennis90a]

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.

What feature do you want?

An indication that shows if a video has already been added to a playlist. Like YouTube does.
What NewPipe could do is show a little check onstead of the plus in the playlist button. If it is clicked(and it has already been added), there could be an option to remove it from a playlist or add it to a playlist.

Why do you want this feature?

Sometimes I end up adding the same video multiple times, because I would not remember if I had already added it.
Also, sometimes I while watching my Watch Later playlist, I would lik3 to remove the video I am watching from the playlist, for which I would have to go to the playlista viewer and remove it from there.

[SameenAhnaf]

Duplicate of #4186