Auto merge of #110693 - clubby789:x-clap-take-2, r=Mark-Simulacrum

Migrate bootstrap to Clap-based argument parsing

Supercedes #108083

I chose to re-do the work rather than rebase the onto the large changes since the original PR. If it's preferred I can instead force-push the original PR to this version.

cc `@jyn514` `@albertlarsan68`

Author: bors