Add more type annotations replacing `any`, mostly in src/printers/

[gnprice]

This is another round of adding real, non-any, type annotations, like #181.

These are focused on some code I was working on bugfixes for today. Those bugfixes themselves aren't yet ready, but in the meantime this part seems independently helpful so I figured I'd share it.

[orta]

Cool, yeah, this all looks good 👍🏻

[gnprice]

Thanks!