Remove ServerExternalMod from OrderManager

OpenRA.Game/Network/OrderManager.cs

@@ -30,7 +30,6 @@ namespace OpenRA.Network
 
 		public string ServerError = null;
 		public bool AuthenticationFailed = false;
-		public ExternalMod ServerExternalMod = null;
 
 		public int NetFrameNumber { get; private set; }
 		public int LocalFrameNumber;

OpenRA.Game/Network/UnitOrders.cs

@@ -192,7 +192,7 @@ namespace OpenRA.Network
 							Game.ExternalMods.TryGetValue(externalKey, out var external))
 						{
 							// The ConnectionFailedLogic will prompt the user to switch mods
-							orderManager.ServerExternalMod = external;
+							CurrentServerSettings.ServerExternalMod = external;
 							orderManager.Connection.Dispose();
 							break;
 						}