Eslint: add comma-dangle always multi-line rule

[simison]

Proposed Changes

• Switch comma-dangle Eslint rule from never to always multi-line
• Apply eslint --fix to all files

(I separated these steps into two commits)

This is kinda paving the way to eventually start using Prettier in the codebase (#932), although it's possible to turn off trailingComma option in Prettier so this isn't strickly necessary.

That said, it's a good convention to have since it's a bit more convenient to re-arrange different lists (variables, imports, etc) alphabetically without comma-hassle. 😁

This will also cause one less line-change in diffs when modifying the end of multi-line lists.

Testing Instructions

• npm run lint passing?

[nicksellen]

I'm a fan of the multiline trailing comma dangle 👍

[mrkvon]

You're fast, guys 😁

Anyways, let's get other PRs rebased! This affects almost everything.

I like this, too. 👍

[simison]

@mrkvon yup, and you can run npm run lint -- --fix to get commas in your PRs after rebasing.