Use Prettier to format both client and server code

[floogulinc]

We should start using Prettier to enforce a common code format and automatically handle actually formatting the code.

After which we can switch to the recommended set of ESLint rules: https://github.com/angular-eslint/angular-eslint/blob/master/packages/eslint-plugin/src/configs/README.md#recommended

[NicMcPhee]

I really would like to get this set up for next semester. I have become super fond of an enforced formatting convention in Rust over the last year, and in the same way annoyed by the lack of consistent formatting in CSci 1301 this semester.

[NicMcPhee]

This doesn't look too hard. I pretty much had it setup for the intro-to-git lab, but ended up undoing that since it didn't seem to make much sense there (esp. since there's no JS/TS there).

I think there are actually two issues here (although I might leave them together here?):

• Setting up formatting on save in VS Code
• Adding a formatting check as part of the GitHub Action checks

The first would be enough if you could guarantee that the only way people would ever alter files was through VSCode, but there's no guarantee of that. So we probably want a GitHub Action check using the prettier CLI as well.

I'll probably set things up to ignore Markdown files. Prettier doesn't seem to do a great job when things get complicated. It mangles GitHub emoticons, and apparently has issues with tables as well.