grassmoor-tracker-thumbnail-proxy: Thumbnail all the Tracker-indexed files
Ship a proof-of-concept user service that listens for new files being indexed in Tracker and proxies their URLs to the thumbnailer to generate previews for them.
This is to paper over the fact that libgrassmoor relies on a external entity to request the generation of the thumbnails it needs. In the past this was done by a downstream patch to Tracker, but since it has been dropped this service provides a stop-gap solution.
The longer term solution would be for libgrassmoor to issue the Queue() calls on its own, which would be far more efficient and clean.
This fixes the display of songs in Frampton: without thumbnails Frampton creates completely transparent actors which cannot be interacted with.