QueueButton: UI for queueing indication and click again to unqueue

When a player clicks the queue button, they join the queue.
Clicking again should then leave the queue.
If enough players join a queue, a game starts and they are removed from every queue they are in (you can queue for multiple different types of game). This needs to happen before any other games start which they might be queued in.

Locate the QueueButton component and the queue-handling entry points, then trace how players join queues and how game start removes them. Done means the button visibly indicates queueing, clicking it again leaves the queue, and starting one game removes those players from every other queue before another game starts.

Written by the indexing model from the issue text.