[racket-dev] New keyword arguments to `racket/file` procedures

The package reorganization also involved some changes to
`racket/file`, which added keyword arguments to, at least,
`find-files`, `delete-directory/files`, `copy-directory/files`, and
`pathlist-closure`. Unfortunately, none of these arguments are
documented.  Should they have documentation, or are they purely
internal? If the latter, I'd like to provide versions without the
arguments for the purpose of Typed Racket, which is sensitive to
whether functions have keyword arguments.

Sam