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

game_server.gd

@@ -6,6 +6,26 @@ func _ready() -> void:
 
 
 func setup_signals() -> void:
-	#MessageBus.subscribe("game_wait_for_connection", _wait_for_connection)
-	#MessageBus.subscribe("game_close_connection", _wait_close_connection)
 	pass
+
+func server_client_connected(id: int) -> void:
+	push_warning("Client Connected... ID: ", id)
+
+	if not Globals.game_data.client1:
+		Globals.game_data.client1 = id
+	elif not Globals.game_data.client2:
+		Globals.game_data.client2 = id
+
+	if Globals.game_data.client1 and Globals.game_data.client2:
+		Globals.multiplayer_data.init_match()
+
+	# TODO: Add watch match feature...
+
+func server_client_disconnected(id: int) -> void:
+	push_warning("Client Disconnected... ID: ", id)
+
+	MessageBus.emit_propagation_clients_only.rpc("game_peer_disconnected", null)
+
+	await get_tree().create_timer(5.0).timeout
+	# NOTE: Quits game server instance.
+	get_tree().quit()