## Summary
This PR moves `empty_parenthesized` such that it's peer to
`parenthesized`, and changes the API to better match that of
`parenthesized` (takes `&str` rather than `StaticText`, has a
`with_dangling_comments` method, etc.).
It may be intentionally _not_ part of `parentheses.rs`, but to me
they're so similar that it makes more sense for them to be in the same
module, with the same API, etc.
c7703e205d