Core/GameObject: Implement GAMEOBJECT_TYPE_NEW_FLAG_DROP

Port From (https://github.com/TrinityCore/TrinityCore/commit/3cfc27f5ca81402ed41973a0206838e7a0352070)

Source/Game/Maps/ZoneScript.cs

@@ -1,6 +1,7 @@
 // Copyright (c) CypherCore <http://github.com/CypherCore> All rights reserved.
 // Licensed under the GNU GENERAL PUBLIC LICENSE. See LICENSE file in the project root for full license information.
 
+using Framework.Constants;
 using Framework.Dynamic;
 using Game.Entities;
 
@@ -40,6 +41,8 @@ namespace Game.Maps
 
         public virtual void ProcessEvent(WorldObject obj, uint eventId, WorldObject invoker) { }
 
+        public virtual void OnFlagStateChange(GameObject flagInBase, FlagState oldValue, FlagState newValue, Player player) { }
+
         protected EventMap _events = new();
     }
 }