`basilisp format` subcommand

[chrisrink10]

It would be useful to include a basilisp format CLI subcommand to format Basilisp code automatically (as cljfmt).

Once #467 is merged, we could even include a keybinding like c-f to allow reformatting REPL code.

[chrisrink10]

https://docs.cider.mx/cider/indent_spec.html

[chrisrink10]

I think in order to do this, we'll need to have some reader function which provide comments as part of the concrete syntax tree.

[chrisrink10]

https://github.com/kkinnear/zprint feels like a nice option too.