use SecureActionButtonTemplate for WatchList items

- The button is a modified version of Blizzard's QuestObjectiveItemButtonTemplate.
- There might be problems when changing the list during combat lockdown. Item activation itself does work in combat, though.
- NxWatchListItem_OnUpdate doesn't follow Carbonite naming conventions, it's just a copy from Blizzard's version.
- Changes in NxQuest.lua are only formatting.