Spotify: Add option to exclude audiobooks from search results

[laurentlbm]

I have a "Basic Family" subscription to Spotify and it doesn't include audiobooks. Unfortunately, the search in Music Assistant still includes them in the results, and if I try to play one, it fails silently.

Ideally, MA would detect that my subscription doesn't include audiobooks and would exclude them automatically from the search. Not sure if that's possible with the Spotify API.
Otherwise, the provider config could have an option to disable support for audiobooks. Thoughts?