Fix Last.fm incorrect API uses

Fixes #2016 (closed)

The audioscrobbler plugin, when used for Last.fm, attempts to use two API methods that don't exist, resulting in HTTP 404 Bad Request errors and hidden sections in the user page UI.

The query to get top tracks with the missing method "library.getTracks" can be replaced with "user.getTopTracks". For similarity, also update the top artists query to use "user.getTopArtists". These reflect the default time window set by the user online in Last.fm preferences.

The query to get recommended artists with "user.getRecommendedArtists" has no simple replacement. There is no API method to get a list of recommended artists. The prior separate streaming/radio API is deprecated and not usable. Therefore, the approach is to remove it from the plugin UI entirely.

Note that most of the lists are given a default "star" icon. This appears to be an intentional change to the Last.fm API; they don't want to be in the free album art API business.

Before: (Note the Top Tracks section is missing)

After: