Core/Auras: Allow SPELL_AURA_MECHANIC_IMMUNITY_MASK to apply aoe/chain targeting immunity

Port From (https://github.com/TrinityCore/TrinityCore/commit/ed0b621d1569a14174a9802027b68dbe4329da69)

Source/Game/Entities/Creature/Creature.cs

@@ -2218,6 +2218,9 @@ namespace Game.Entities
 
                 foreach (AuraType aura in immunities.Aura)
                     ApplySpellImmune(placeholderSpellId, SpellImmunity.State, aura, apply);
+
+                if (immunities.Other != SpellOtherImmunity.None)
+                    ApplySpellImmune(placeholderSpellId, SpellImmunity.Other, (byte)immunities.Other, apply);
             }
 
             // unapply template immunities (in case we're updating entry)

Source/Game/Entities/Unit/Unit.Spells.cs

@@ -1384,6 +1384,16 @@ namespace Game.Entities
             return mask;
         }
 
+        public SpellOtherImmunity GetSpellOtherImmunityMask()
+        {
+            SpellOtherImmunity mask = 0;
+            var damageList = m_spellImmune[(int)SpellImmunity.Other];
+            foreach (var pair in damageList)
+                mask |= (SpellOtherImmunity)pair.Key;
+
+            return mask;
+        }
+
         public virtual bool IsImmunedToSpellEffect(SpellInfo spellInfo, SpellEffectInfo spellEffectInfo, WorldObject caster, bool requireImmunityPurgesEffectAttribute = false)
         {
             if (spellInfo == null)