Add ESLint

[ayushmanchhabra]

No description provided.

[TheJaredWilcurt]

There are a lot of stylistic rules that could be applied to make the code more consistent.

Here is my ruleset for reference:

• https://github.com/tjw-lint/eslint-config-tjw-base/blob/main/index.js

Ones that come to mind when looking over this PR:

• Sometimes we add an extra comma at the end, sometimes we don't. Should probably add the comma-dangle rule to enforce that one way or the other.
• Sometimes there is a space after a function name during a declaration, other times there is not. space-before-function-paren can enforce this, and the best rule would be to always have a space, so that the parenthesis only touch the name when the code is being executed to make a clear visual distinction.

Feel free to look through that ruleset and read the comments that explain what each rule does and port over whatever parts you want.

[ayushmanchhabra]

Sounds good!

[ayushmanchhabra]

I can open a new PR instead. There's no point in trying to revert changes made by Prettier.