Per conversation in clap/clap#4443 this issue is for discussion around adding
an ansi-to-roff conversion library.

In epage/anstyle#4, I contrast different ANSI parsing libraries. For a first
round, feel free to use what is easiest as long as it as a good license. I'm
less concerned about clap_mangens build times. We can then iterate on it as
clap needs to adopt an ANSI parser.

clap_mangen is in its very early stages; nothing is set in stone.