Function getIntersectionWordSets

Returns a potentially infinite iterable of word sets accepted by both given transition iterables.

This function provides the following guarantees:

1. Word sets are guaranteed to be yielded in the order of increasing length. (Word sets of equal lengths may be yielded in any order.)
2. No character set of the yielded word sets is empty.

This is roughly equivalent to NFA.fromIntersection(left, right).wordSets() but implemented more efficiently.