[FEATURE] Capture more song metadata and add to the queue song info

[xxxserxxx]

Subsonic servers provide a lot of information about songs that isn't currently captured by the entity struct; in particular, it'd be nice to have:

1. Genre -- which would allow all sorts of interesting functionality
2. Cover art
3. Year of release

Then there are long-tail data such as bitrate, file type, path to the file on the server, and so on. I think for the purposes of this ticket, the 3 items above would be easy and useful wins.