feat(Core/ScriptMgr): add new hook OnAfterUnloadAllMaps (#10279)

* feat(Core/ScriptMgr): add new hook

* add desc

* Update src/server/game/Scripting/ScriptDefines/WorldScript.cpp

src/server/worldserver/Main.cpp

@@ -329,6 +329,8 @@ int main(int argc, char** argv)
 
         sOutdoorPvPMgr->Die();                     // unload it before MapMgr
         sMapMgr->UnloadAll();                      // unload all grids (including locked in memory)
+
+        sScriptMgr->OnAfterUnloadAllMaps();
     });
 
     // Start the Remote Access port (acceptor) if enabled