Create port forwarding for correct port with UPnP

Up to know the UPnP logic ignored the port a user was hosting a game on
and always added a port forwarding for the default port UDP 20595. This
commit fixes that, so a port forwarding is added for the actual port a
game is hosted on.

(cherry picked from commit fcd3fc2aa3)
Signed-off-by: Itms <itms@wildfiregames.com>

source/network/NetServer.h

@@ -436,7 +436,7 @@ private:
 	/**
 	 * Try to find a UPnP root on the network and setup port forwarding.
 	 */
-	static void SetupUPnP();
+	static void SetupUPnP(const u16 port);
 	std::thread m_UPnPThread;
 #endif