Core/Combat: Disable triggers entering combat

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

Source/Framework/Constants/CreatureConst.cs

@@ -210,6 +210,7 @@ namespace Framework.Constants
         UnitIsQuestBoss = 0x80000000 // Not verified
     }
 
+    [Flags]
     public enum CreatureFlagsExtra : uint
     {
         InstanceBind = 0x01,       // Creature Kill Bind Instance With Killer And Killer'S Group
@@ -225,7 +226,7 @@ namespace Framework.Constants
         GhostVisibility = 0x400,       // creature will be only visible for dead players
         UseOffhandAttack = 0x800, // creature will use offhand attacks
         NoSellVendor = 0x1000,       // players can't sell items to this vendor
-        Unused13 = 0x2000,
+        NoCombat = 0x2000,         // creature is not allowed to enter combat
         Worldevent = 0x4000,       // Custom Flag For World Event Creatures (Left Room For Merging)
         Guard = 0x8000,       // Creature Is Guard
         Unused16 = 0x00010000,
@@ -246,7 +247,7 @@ namespace Framework.Constants
         Unused31 = 0x80000000,
 
         // Masks
-        AllUnused = (Unused13 | Unused16 | Unused22 | Unused23 | Unused24 | Unused25 | Unused26 | Unused27 | Unused31),
+        AllUnused = (Unused16 | Unused22 | Unused23 | Unused24 | Unused25 | Unused26 | Unused27 | Unused31),
 
         DBAllowed = (0xFFFFFFFF & ~(AllUnused | DungeonBoss))
     }

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

@@ -3098,6 +3098,10 @@ 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();}