Core/Combat: Disable triggers entering combat

Port From (https://github.com/TrinityCore/TrinityCore/commit/1dfcb7086e17902f0904ee6c09bc55a229b65cc1)

Source/Game/Combat/CombatManager.cs

@@ -57,6 +57,12 @@ namespace Game.Combat
                 return false;
             if (a.HasUnitState(UnitState.InFlight) || b.HasUnitState(UnitState.InFlight))
                 return false;
+            Creature aCreature = a.ToCreature();
+            if (aCreature?.IsCombatDisallowed())
+                return false;
+            Creature bCreature = b.ToCreature();
+            if (bCreature?.IsCombatDisallowed())
+                return false;
             if (a.IsFriendlyTo(b) || b.IsFriendlyTo(a))
                 return false;
             Player playerA = a.GetCharmerOrOwnerPlayerOrPlayerItself();

Source/Game/Entities/Creature/Creature.cs

@@ -3098,7 +3098,11 @@ namespace Game.Entities
         {
             return GetCreatureTemplate().FlagsExtra.HasAnyFlag(CreatureFlagsExtra.Guard);
         }
-
+        bool IsCombatDisallowed()
+        {
+            return GetCreatureTemplate().FlagsExtra.HasFlag(CreatureFlagsExtra.NoCombat);
+        }
+        
         public bool CanWalk() { return GetMovementTemplate().IsGroundAllowed(); }
         public override bool CanSwim() { return GetMovementTemplate().IsSwimAllowed() || IsPet();}
         public override bool CanFly()  { return GetMovementTemplate().IsFlightAllowed() || IsFlying(); }