Core/Game: Rewrote the ScriptMgr to support script reloading.

* Finally this commit enables dynamic script hotswapping
  and finished the PR #15671.
* Split the storage layout to use optimized storages
  for database bound and unbound scripts.
* Add several unload workers to reload scripts correctly
  -> Requires further investigation.
* Fixes memory leaks in ScriptMgr when dropping invalid scripts.
* Fixes VehicleScripts
* Makes OutdoorPvP scripts reloadable
* Makes InstanceMapScripts reloadable
* Makes CommandScripts reloadable

src/server/game/DungeonFinding/LFGScripts.cpp

@@ -241,4 +241,10 @@ void LFGGroupScript::OnInviteMember(Group* group, ObjectGuid guid)
         sLFGMgr->LeaveLfg(leader);
 }
 
+void AddSC_LFGScripts()
+{
+    new LFGPlayerScript();
+    new LFGGroupScript();
+}
+
 } // namespace lfg