Codechange: Define GRFConfigList alias and pass by reference. (#13358)

This adds the distinction between a single GRFConfig and a GRFConfig list, and simplifies how GRFConfig lists are passed to various functions.

src/network/network_query.cpp

@@ -120,7 +120,7 @@ NetworkRecvStatus QueryNetworkGameSocketHandler::Receive_SERVER_GAME_INFO(Packet
 	NetworkGameList *item = NetworkGameListAddItem(this->connection_string);
 
 	/* Clear any existing GRFConfig chain. */
-	ClearGRFConfigList(&item->info.grfconfig);
+	ClearGRFConfigList(item->info.grfconfig);
 	/* Retrieve the NetworkGameInfo from the packet. */
 	DeserializeNetworkGameInfo(p, item->info);
 	/* Check for compatability with the client. */