Move react-scripts/config/jest into react-dev-utils

Created by: marcofugaro

Is your proposal related to a problem?

All the files in the folder react-scripts/config/jest are util transforms used in a jest.config.js. They're really useful and very common, so that they're described also in the official guide of jest.

I am building a custom jest config, and would rather use those files than write my own, so I added react-script as a dependency and am importing those files from there. However I would prefer if they'd be in react-dev-utils instead, because that's more semantically correct and I don't want to install another dependency with a lot of other dependencies I don't need inside, just for a couple of functions.

Describe the solution you'd like

Move react-scripts/config/jest into react-dev-utils.