Integrate eslint

[php-coder]

https://eslint.org/

[php-coder]

https://www.npmjs.com/package/eslint-plugin-react
https://github.com/evcohen/eslint-plugin-jsx-a11y

[php-coder]

• https://github.com/jest-community/eslint-plugin-jest
• https://github.com/dangreenisrael/eslint-plugin-jest-formatting
• https://github.com/testing-library/eslint-plugin-testing-library
• https://github.com/nickdeis/eslint-plugin-notice
• https://github.com/paleite/eslint-plugin-diff
• https://github.com/BenoitZugmeyer/eslint-plugin-html

[php-coder]

In the light of #1669 we don't need this.