Switch to eslint-based import sorting

[ejizba]

Related to this discussion, I wanted to switch off of VS Code's organize imports feature and onto an eslint-based one. I split this PR into two commits for easier review: one to configure eslint and one to auto-fix the repo based on the new config.

Background (feel free to ignore if not interested)

I believe VS Code is using a built-in feature of TypeScript's language service that sorts imports (not an eslint rule). I can't find the feature documented by TypeScript, but it was announced here.

Turns out there are a ton of ways to do this 😅. These are the options I considered:

1. eslint's built-in sort-imports rule: very basic features with no auto-fix
2. prettier-plugin-organize-imports: uses the TypeScript language service and explicitly mentions it should be the same as VS Code's feature. Not a super popular package, though
3. eslint-plugin-import: Lots of different rules and options, some of which support auto-fix
4. eslint-plugin-simple-import-sort: A more opinionated package that prioritizes auto-fix

I liked option 4 the best. "auto-fix" is a priority for me on this and they knocked it out of the park. I followed their example config and made one tweak to remove whitespace between groups.

[castrodd]

Looks great!