Load track data into player2 up-front

[shish]

90% of queue_items.json is track data[1] - if we loaded all of track_list.json up-front, and made it so that queue_items only contained track_id fields to cross-reference, that'd make the updates much smaller

[1] Testing with a 3 hour long queue, queue_items.json is 250KB, with track data removed it goes down to 22KB

(This approach would be incompatible with browser1, because browser1 requires that all data to render a single page is fetched in one go, no cross-referencing - so it'd need to happen after browser2 becomes official)

[calaldees]

58 #91

This ticket proposes loading track_list.json into player2 like browser2 does. Track data is now available via a static file (this dramatically improves performance) when website is deprecated, track data will not accessible via a track api.

[shish]

This is done now - tracks.json contains all the track data, queue.json only contains track IDs