Scripts/Spells: Implement OnPrecast scripting hook for spell scripts

Port From (https://github.com/TrinityCore/TrinityCore/commit/12d00e2e5f7e2cc7efe1ea8d126f9408055c05f8)

Source/Framework/Constants/ScriptsConst.cs

@@ -44,7 +44,8 @@ namespace Framework.Constants
         OnCast,
         OnResistAbsorbCalculation,
         AfterCast,
-        CalcCritChance
+        CalcCritChance,
+        OnPrecast
     }
 
     // AuraScript interface - enum used for runtime checks of script function calls

Source/Game/Scripting/SpellScript.cs

@@ -502,6 +502,8 @@ namespace Game.Scripting
                 || m_currentScriptState == (byte)SpellScriptHookType.EffectSuccessfulDispel;
         }
 
+        public virtual void OnPrecast() { }
+
         Spell m_spell;
         uint m_hitPreventEffectMask;
         uint m_hitPreventDefaultEffectMask;

Source/Game/Spells/Spell.cs

@@ -2413,6 +2413,8 @@ namespace Game.Spells
             // set timer base at cast time
             ReSetTimer();
 
+            CallScriptOnPrecastHandler();
+
             Log.outDebug(LogFilter.Spells, "Spell.prepare: spell id {0} source {1} caster {2} customCastFlags {3} mask {4}", m_spellInfo.Id, m_caster.GetEntry(), m_originalCaster != null ? (int)m_originalCaster.GetEntry() : -1, _triggeredCastFlags, m_targets.GetTargetMask());
 
             if (m_spellInfo.HasAttribute(SpellAttr12.StartCooldownOnCastStart))
@@ -7131,6 +7133,16 @@ namespace Game.Spells
             }
         }
 
+        void CallScriptOnPrecastHandler()
+        {
+            foreach (var script in m_loadedScripts)
+            {
+                script._PrepareScriptCall(SpellScriptHookType.OnPrecast);
+                script.OnPrecast();
+                script._FinishScriptCall();
+            }
+        }
+
         void CallScriptBeforeCastHandlers()
         {
             foreach (var script in m_loadedScripts)