Download playlists, collections and albums for offline music listening

[Arne-DH]

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

The problem occurs when trying to listen offline to music, currently the only way to download songs trough Jellyfin is by downloading the individual song to your system.

Describe the solution you'd like

2 possible scenario's:

1- the easiest is just a further implementation of the current feature of downloading songs, so that you can download entire playlists to the filesystem instead of individual songs .
2- A other solution would be to implement a system simular to spotify so that you can download entire playlists to a specified location on the device and keep using Jellyfin for listening to music instead of just having a bunch of .mp3 files on your filesystem. This is in my opinion the preffered solution but is more complicated to implement and I would already be happy with the first solution implemented.

Describe alternatives you've considered

Download every single song sepperatly in the playlist but that's a massive pain for playlists with over a 100 songs.

Additional context

Add download album/playlist button: