[ESLint] Dogfood the @elastic/eslint-plugin-eui

[weronikaolejniczak]

The purpose of this issue is to use our plugin for the ESLint configuration in packages/eui. The goal is to be able to spot the same types of issues we warn against in our own code.

Details

The point is to install @elastic/eslint-plugin-eui in packages/eui and set it to workspace dependency. Then, use it in eui/packages/eui/.eslintrc.js:

module.exports = {
  extends: [
    // ...
    'plugin:@elastic/eui/recommended',
  ],
  plugins: [
    '@elastic/eui',
  ],
}

Acceptance criteria

• @elastic/eslint-plugin-eui is installed in packages/eui,
• our recommended list is extended in packages/eui ESLint configuration,
• we validate that warnings are reported.