Add prettier support and enforce with commit hook

[vegetabill]

If we're planning on a lot of different contributions, it might be nice to have a consistent format for the code.

See comments below for more info.

[vegetabill]

This guide covers what we might want (except we won't need any of the React-related plugins):

https://medium.com/@loclghst/set-up-eslint-prettier-and-pre-commit-hooks-using-husky-for-react-73e7a51cda26

Feel free to use a different strategy if you know of a simpler one.

[swarna-gopalan]

@vegetabill - I can take this one as part of GraceHopperOSD