Create a simple terminal-based example game

[alice-i-cecile]

With a CLI crate in tree for our examples, this is a great opportunity to show off how Bevy can be used in less conventional contexts. This will make heavy use of a custom runner :)

          Switched to google's `argh` crate for command line parsing. It's small, has only dependencies that we already have (syn, quote, serde, proc-macro2), and is still derive-based so brings most of the ergonomics we need. FromArgs has a blanket implementation for anything that implements FromStr. This means we have to implement FromStr for enums.

Originally posted by @superdump in #9596 (comment)