[Enhancement] Allow choosing a default/preferred playlist for adding videos

[Eldemarkki]

Is your enhancement request related to a problem? Please describe.

I have two playlists, one for videos that I want to watch later, and one for videos that I particularly liked and may want to rewatch. I add videos to the watch later playlist much more often than to the other one. Due to alphabetical sorting I always need to manually switch the playlist, because the sorting causes my less used playlist to appear as the default.

Describe the solution you'd like

Add a new setting for choosing the default playlist. This playlist will then be auto-selected in the video player view, and I can simply click "Add to playlist" without needing to change the playlist.

Describe alternatives you've considered

A dedicated watch later feature, but there is already an issue for that: #408

Additional context