feat(Core/Unit): New helper IsClass and script hook OnPlayerIsClass (#18243)

* Class Comparison Logic Encapsulation - Parity

* Add Context to IsClass

* Add Unit IsClass script hook

* Replace additional getClass with IsClass

* Update CanUseItem to replace getClass with IsClass

* Add separate context for pet vs ability

* Change Create to Init since not all referenced contexts are creation

* Align spacing in ClassContext

* Drop context on LFGManager max power

* Update IsClass context that wraps around Missle Barrage

* Rename context for swapping weapons

* Be more specific than CLASS_CONTEXT_TALENT

* Remove duplicate context

* Moved IsClass Hook to Player

* Removed unused parameter in virtual base function

* Added maybe_unused to IsClass virtual in order to compile

To match the override signature, the virtual base needs to include the parameter in question, so using [maybe_unused] to signal to the compiler to allow it

* Remove extra blank line

* Add ABILITY_REACTIVE context

* Add context for PET_CHARM

* Remove explicit nullopt check per review

* Code Readability - Change if to if else in pet

Due to the return pattern, this doesn't change functionality in any way

* Add OnPlayer to disambiguate

---------

Co-authored-by: NathanHandley <nathanhandley@protonmail.com>

src/server/game/Scripting/ScriptDefines/PlayerScript.cpp

@@ -1038,6 +1038,19 @@ bool ScriptMgr::CanRepopAtGraveyard(Player* player)
     return true;
 }
 
+Optional<bool> ScriptMgr::OnPlayerIsClass(Player const* player, Classes unitClass, ClassContext context)
+{
+    if (ScriptRegistry<PlayerScript>::ScriptPointerList.empty())
+        return {};
+    for (auto const& [scriptID, script] : ScriptRegistry<PlayerScript>::ScriptPointerList)
+    {
+        Optional<bool> scriptResult = script->OnPlayerIsClass(player, unitClass, context);
+        if (scriptResult)
+            return scriptResult;
+    }
+    return {};
+}
+
 void ScriptMgr::OnGetMaxSkillValue(Player* player, uint32 skill, int32& result, bool IsPure)
 {
     ExecuteScript<PlayerScript>([&](PlayerScript* script)