Add a layouter based on JP Bernardy's prettiest printer

Paper: https://jyp.github.io/pdf/Prettiest.pdf
Implementation: https://hackage.haskell.org/package/pretty-compact
Old blog post: https://jyp.github.io/posts/towards-the-prettiest-printer.html

I'm mostly curious how results and performance would compare to `layoutSmart`.

Read the linked Prettiest paper, the pretty-compact implementation, and the older blog post first, then inspect the repository's existing layoutSmart behavior. Define the layouter's intended comparison criteria before implementing it, with completion requiring comparable results and performance measurements against layoutSmart.

Written by the indexing model from the issue text.