For extract-css, do not use the obsolete batch package anymore

[binarykitchen]

Problem

extract-css relies on a broken npm package named batch, see https://github.com/jonkemp/inline-css/blob/master/packages/extract-css/package.json#L17

The npm package batch has issues, is broken, and isn't maintained for 7 years: https://github.com/visionmedia/batch/blob/master/index.js

The cause is, it requires the emitter package which isn't listed under dependencies and breaks modern TS builds.

A possible solution would be to replace batch with another package with similar functionality.