change behaviour of chain quests (scrolls to owner only) - fixes https://github.com/HabitRPG/habitrpg/issues/2715

Requires https://github.com/HabitRPG/habitrpg-shared/pull/303

Allows quests to specify 'itemsForOwner' in addition to or as well as 'items'. Anything listed under itemsForOwner will be given to only the quest owner when the quest is complete. Anything listed under items will be given to all participants.