Core/Spells: Allow cancelling spell missiles without cancelling the entire spell

Port From (https://github.com/TrinityCore/TrinityCore/commit/ed98146d317f9b956e8ca23524631cdd2388492b)

Source/Game/Entities/Unit/Unit.cs

@@ -1212,9 +1212,11 @@ namespace Game.Entities
             SendMessageToSet(cancelSpellVisualKit, true);
         }
 
-        public void CancelSpellMissiles(uint spellId, bool reverseMissile = false)
+        public void CancelSpellMissiles(uint spellId, bool reverseMissile = false, bool abortSpell = false)
         {
             bool hasMissile = false;
+            if (abortSpell)
+            {
                 foreach (var pair in m_Events.GetEvents())
                 {
                     Spell spell = Spell.ExtractSpellFromEvent(pair.Value);
@@ -1227,6 +1229,9 @@ namespace Game.Entities
                         }
                     }
                 }
+            }
+            else
+                hasMissile = true;
 
             if (hasMissile)
             {