Core/AI: Implemented conversation ai

Port From (https://github.com/TrinityCore/TrinityCore/commit/309ba22a15e5e0b4321b99f7157ccb18e0adc8dd)

Source/Game/AI/AISelector.cs

@@ -110,5 +110,14 @@ namespace Game.AI
                 _ => new GameObjectAI(go),
             };
         }
+
+        public static ConversationAI SelectConversationAI(Conversation conversation)
+        {
+            ConversationAI ai = Global.ScriptMgr.GetConversationAI(conversation);
+            if ( ai != null)
+                return ai;
+
+            return new NullConversationAI(conversation, Global.ObjectMgr.GetScriptId("NullConversationAI", false));
+        }
     }
 }

Source/Game/AI/CoreAI/ConversationAI.cs

@@ -0,0 +1,55 @@
+// 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.Spells;
+
+namespace Game.AI
+{
+    public class ConversationAI
+    {
+        uint _scriptId;
+        public Conversation conversation;
+
+        public ConversationAI(Conversation c, uint scriptId = 0)
+        {
+            _scriptId = scriptId != 0 ? scriptId : c.GetScriptId();
+            conversation = c;
+
+            Cypher.Assert(_scriptId != 0, "A ConversationAI was initialized with an invalid scriptId!");
+        }
+
+        // Called when the Conversation has just been initialized, just before added to map
+        public virtual void OnInitialize() { }
+
+        // Called when Conversation is created but not added to Map yet.
+        public virtual void OnCreate(Unit creator) { }
+
+        // Called when Conversation is started
+        public virtual void OnStart() { }
+
+        // Called when player sends CMSG_CONVERSATION_LINE_STARTED with valid conversation guid
+        public virtual void OnLineStarted(uint lineId, Player sender) { }
+
+        // Called for each update tick
+        public virtual void OnUpdate(uint diff) { }
+
+        // Called when the Conversation is removed
+        public virtual void OnRemove() { }
+
+        // Pass parameters between AI
+        public virtual void DoAction(int param) { }
+        public virtual uint GetData(uint id = 0) { return 0; }
+        public virtual void SetData(uint id, uint value) { }
+        public virtual void SetGUID(ObjectGuid guid, int id = 0) { }
+        public virtual ObjectGuid GetGUID(int id = 0) { return ObjectGuid.Empty; }
+
+        // Gets the id of the AI (script id)
+        public uint GetId() { return _scriptId; }
+    }
+
+    class NullConversationAI : ConversationAI
+    {
+        public NullConversationAI(Conversation c, uint scriptId) : base(c, scriptId) { }
+    }
+}