A new command line option `--syntax-highlighting` is provided; it takes
the values `none`, `default`, `idiomatic`, a style name, or a path to a
theme file. It replaces the `--no-highlighting`, `--highlighting-style`,
and `--listings` options.
The `writerListings` and `writerHighlightStyle` fields of the
`WriterOptions` type are replaced with `writerHighlightStyle`.
Closes: #10525