Client request to join table
The identifier of the table the player wishes to join
Whether to join as spectator (when true) or not (when false or omitted).
The seat number of the seat to join in. If the seat number is negative or not given, the first available seat will be joined.
JOIN is sent from client to the server to request a table join. The server will respond with RESULT telling us the success of the action. If the action was successful the client will also receive a JOIN, which we should act upon. If the join succeeds it is likely an UPDATE of type 'table' will also be necessary.