Core/Spells: Implement spell queue

Port From (https://github.com/TrinityCore/TrinityCore/commit/27019a62a4294f8dd48d975f85b1907c5adee0e3)

Source/Game/Spells/SpellCastRequest.cs

@@ -0,0 +1,37 @@
+// 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 Game.Entities;
+using Game.Networking.Packets;
+
+namespace Game.Spells
+{
+    public class SpellCastRequestItemData
+    {
+        public byte PackSlot;
+        public byte Slot;
+        public ObjectGuid CastItem;
+
+        public SpellCastRequestItemData(byte packSlot, byte slot, ObjectGuid castItem)
+        {
+            PackSlot = packSlot;
+            Slot = slot;
+            CastItem = castItem;
+        }
+    }
+
+    public class SpellCastRequest
+    {
+        public SpellCastRequestPkt CastRequest;
+        public ObjectGuid CastingUnitGUID;
+        public SpellCastRequestItemData ItemData;
+
+        public SpellCastRequest(SpellCastRequestPkt castRequest, ObjectGuid castingUnitGUID, SpellCastRequestItemData? itemData = null)
+        {
+            CastRequest = castRequest;
+            CastingUnitGUID = castingUnitGUID;
+            ItemData = itemData;
+        }
+    }
+
+}