Core/Spells: Implemented evoker empower spell mechanic

Port From (https://github.com/TrinityCore/TrinityCore/commit/a39d0db9ec64f6bf38716abaade5b7835f2db338)

Source/Game/Scripting/SpellScript.cs

@@ -174,6 +174,7 @@ namespace Game.Scripting
         public delegate void SpellObjectAreaTargetSelectFnType(List<WorldObject> targets);
         public delegate void SpellObjectTargetSelectFnType(ref WorldObject targets);
         public delegate void SpellDestinationTargetSelectFnType(ref SpellDestination dest);
+        public delegate void SpellEmpowerStageFnType(int completedStagesCount);
 
         public class CastHandler
         {
@@ -232,6 +233,21 @@ namespace Game.Scripting
             }
         }
 
+        public class EmpowerStageCompletedHandler
+        {
+            SpellEmpowerStageFnType _callImpl;
+
+            public EmpowerStageCompletedHandler(SpellEmpowerStageFnType handler)
+            {
+                _callImpl = handler;
+            }
+
+            public void Call(int completedStagesCount)
+            {
+                _callImpl(completedStagesCount);
+            }
+        }
+
         public class EffectHandler : EffectHook
         {
             SpellEffectName _effName;
@@ -572,6 +588,14 @@ namespace Game.Scripting
         // where function is void function(DamageInfo damageInfo, ref uint resistAmount, ref int absorbAmount)
         public List<OnCalculateResistAbsorbHandler> OnCalculateResistAbsorb = new();
 
+        // example: OnEmpowerStageCompleted += SpellOnEmpowerStageCompletedFn(class::function);
+        // where function is void function(int32 completedStages)
+        public List<EmpowerStageCompletedHandler> OnEmpowerStageCompleted = new();
+
+        // example: OnEmpowerCompleted += SpellOnEmpowerCompletedFn(class::function);
+        // where function is void function(int32 completedStages)
+        public List<EmpowerStageCompletedHandler> OnEmpowerCompleted = new();
+
         // where function is void function(uint effIndex)
         public List<EffectHandler> OnEffectLaunch = new();
         public List<EffectHandler> OnEffectLaunchTarget = new();
@@ -621,6 +645,8 @@ namespace Game.Scripting
         // 14. OnEffectHitTarget - executed just before specified effect handler call - called for each target from spell target map
         // 15. OnHit - executed just before spell deals damage and procs auras - when spell hits target - called for each target from spell target map
         // 16. AfterHit - executed just after spell finishes all it's jobs for target - called for each target from spell target map
+        // 17. OnEmpowerStageCompleted - executed when empowered spell completes each stage
+        // 18. OnEmpowerCompleted - executed when empowered spell is released
 
         //
         // methods allowing interaction with Spell object