There's just starting to be a lot going on, so I pulled them out into
here!
I also considered a like, `Item::DyeworksStatus` class, and then you'd
go like, `item.dyeworks.buyable?`. But idk, I think it's nice that the
current API is simple for callers, and being able to do things like
`items.filter(&:dyeworks_buyable?)` is pretty darn convenient.
This solution lets us keep the increasing number of Dyeworks methods
from polluting the main `item.rb`, while still keeping the API
identical!
