streamline TS; prettier via eslint

[twhid]

Two main changes in this PR:

1. TS incorporated into 1 eslint config. This allows consumers to use overrides to target ts-only files
2. prettier is run via eslint. This allows more streamlined eslint commands for ci and precommit hooks

Also, only load flowtype rules for js(x) files

[hellatan]

I think you have to update the peerDeps here if you're introducing version 6. Not sure why I did this range style instead of just the caret.

[hellatan]

This is marked as a dev/peerDep in the individual packages. You'll need to update those references as well.

[hellatan]

You can't combine this file and the index file?

[twhid]

I'll play around with it a bit more.

[twhid]

Perhaps I'm simply not up-to-date on how overrides work vis a vis extends, but when I add the typescript override to the index file, I get an assertion error from eslint. There's an issue open on the eslint repo that seems to be relevant to the error I'm running into.

So, the way I worked around that was to create a typescript file and the consumer needs to add an override, ie:

module.exports = {
    extends: ['eslint-config-1stdibs'],
    overrides: [
        {
            files: ['*.{ts,tsx}'],
            extends: ['eslint-config-1stdibs/typescript'].map(require.resolve),
            parser: '@typescript-eslint/parser',
            parserOptions: {
                project: './tsconfig.json',
            },
        },
    ],
};

[hellatan]

The consumers will have one .eslintrc file then?

Do you need the require.resolve in the override section even if it's in the consumer?

[twhid]

Yup. One file.

[twhid]

I've updated dev and peer deps everywhere to make eslint's version consistent. I'll update with release versions once everyone agrees on the changes in the private repo consuming this package.