Format files with `dprint`

[mgeisler]

The dprint formatter is a flexible system which will use sandboxed WebAssembly formatters to format our code (mostly: it calls out to rustfmt for Rust code).

A particularly interesting feature is that dprint can format Rust code blocks in the Markdown files. However, before we turn that on, we need to have a way to normalize the Markdown text as it is extracted1. That is so that the word put into the translations is kept after the reformatting.