* Fixes#4644.
* Initialize all battleground queues at startup to reduce overhead of creation/deletion during live server.
* Removes lots of duplicate code between team checks.
* Adds missing checks for script commands bg_leave and bg_desert to only warp players out using the Battleground Queue System.
* Adds documentation for script commands bg_leave and bg_desert to state players will be warped out after when using the Battleground Queue System.
* Optimizes join logic to add new players to the end of the queue rather than the front.
* Cleans up the client messages so certain responses are cleared when they need to be.
Thanks to @Balferian and @Lemongrass3110!
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