refactor: improve multiplayer connection lifecycle

* Move client/server connection handling into game-specific networking classes
* Add multiplayer data reset for disconnected clients
* Clean up invalid MessageBus listeners after disconnects
* Persist lobby host address and port in game data
* Standardize the default server port to 8080
* Increase server address input length to support valid addresses
* Remove obsolete connection and match initialization logic from base networking

scripts/client_networking.gd

@@ -8,6 +8,7 @@ func start_client(address: String = "127.0.0.1", port: int = 8080) -> void:
 	if peer: return
 
 	push_warning("Client Starting... Address: ", address, " Port: ", port)
+	# TODO: Add throbber or other indication of connection attempt.
 
 	peer = ENetMultiplayerPeer.new()
 	peer.create_client(address, port)