Youtube-player: add @input for youtube playlistId

### Feature Description

Currently, you can load a video using the `videoId` input. But a playlist has to be loaded via the `playerVars.list`.
Can we make the loading of media a bit more consistent and add a `playlistId` input for us to use?
Internally that can just add it to the playerVars if that is how Youtube likes it.

### Use Case

Loading of video or playlist Ids using Angular inputs and not having to use playerVars.

Start at the Youtube-player component and trace how the videoId input is applied to playerVars. Add the parallel playlistId input as described, then verify that playlist loading works through an Angular input while existing videoId behavior remains unchanged.

Written by the indexing model from the issue text.