Core/Creatures: Allow disabling melee attacks for all creatures, not just the ones using SAI

Port From (https://github.com/TrinityCore/TrinityCore/commit/d26d38075cdb56dcef77f05276a360e717cc5032)

Source/Game/Entities/Creature/Creature.cs

@@ -3246,6 +3246,10 @@ namespace Game.Entities
         public override SpellSchoolMask GetMeleeDamageSchoolMask(WeaponAttackType attackType = WeaponAttackType.BaseAttack) { return m_meleeDamageSchoolMask; }
         public void SetMeleeDamageSchool(SpellSchools school) { m_meleeDamageSchoolMask = (SpellSchoolMask)(1 << (int)school); }
 
+        public bool CanMelee() { return !_staticFlags.HasFlag(CreatureStaticFlags.NoMelee); }
+
+        public void SetCanMelee(bool canMelee) { _staticFlags.ApplyFlag(CreatureStaticFlags.NoMelee, !canMelee); }
+        
         public sbyte GetOriginalEquipmentId() { return m_originalEquipmentId; }
         public byte GetCurrentEquipmentId() { return m_equipmentId; }
         public void SetCurrentEquipmentId(byte id) { m_equipmentId = id; }

Source/Game/Entities/Unit/Unit.Combat.cs

@@ -258,8 +258,14 @@ namespace Game.Entities
 
             Creature creature = ToCreature();
             // creatures cannot attack while evading
-            if (creature != null && creature.IsInEvadeMode())
-                return false;
+            if (creature != null)
+            {
+                if (creature.IsInEvadeMode())
+                    return false;
+
+                if (!creature.CanMelee())
+                    meleeAttack = false;
+            }
 
             // nobody can attack GM in GM-mode
             if (victim.IsTypeId(TypeId.Player))