Add tracking for Cache of Timewarped Treasures (?)

[rdw-software]

It seems to contain lots of relevant items. But is it worth tracking? This would be blocked by #160 as well (or require more hacks).

See https://www.wowhead.com/item=208095/cache-of-timewarped-treasures#contains

( I haven't checked if there are other bags like this one in Retail now)