Core/SAI: implement SMART_ACTION_ATTACK_STOP

Port From (https://github.com/TrinityCore/TrinityCore/commit/38be5e361e072edec6cfec584db9182ea3ad4450)

Source/Framework/Constants/SmartAIConst.cs

@@ -300,7 +300,7 @@ namespace Framework.Constants
         MountToEntryOrModel = 43,     // CreatureTemplate Entry(Param1) Or Modelid (Param2) (Or 0 For Both To Dismount)
         SetIngamePhaseId = 44,     // Id
         SetData = 45,     // Field, Data (Only Creature Todo)
-        //46 Unused
+        AttackStop = 46,
         SetVisibility = 47,     // On/Off
         SetActive = 48,     // No Params
         AttackStart = 49,     //

Source/Game/AI/SmartScripts/SmartAIManager.cs

@@ -1529,6 +1529,7 @@ namespace Game.AI
                 case SmartActions.CallForHelp:
                 case SmartActions.SetData:
                 case SmartActions.SetVisibility:
+                case SmartActions.AttackStop:
                 case SmartActions.WpPause:
                 case SmartActions.SetDisableGravity:
                 case SmartActions.SetCanFly:

Source/Game/AI/SmartScripts/SmartScript.cs

@@ -1117,6 +1117,16 @@ namespace Game.AI
                     }
                     break;
                 }
+                case SmartActions.AttackStop:
+                {
+                    foreach (var target in targets)
+                    {
+                        var unitTarget = target.ToUnit();
+                        if (unitTarget != null)
+                            unitTarget.AttackStop();
+                    }
+                    break;
+                }
                 case SmartActions.MoveOffset:
                 {
                     foreach (var target in targets)