Remove unnecessary dependencies

Created by: gaearon

Update: claimed by @alamgird

Now that we have a monorepo structure, we can pull out some of the small and annoying dependencies from packages/react-scripts/package.json into packages/react-dev-utils/package.json and provide helpers there instead.

I started this in https://github.com/facebookincubator/create-react-app/pull/723 but packages/react-scripts/scripts/build.js is still pretty noisy, and we could extract the code to compare build sizes (and maybe something else) into react-dev-utils.

I recommend the following workflow:

1. Look at packages/react-scripts/package.json
2. See where these dependencies get used
3. If they seem non-essential and too low-level, figure out how to hide them in react-dev-utils
4. Repeat

This is a contributor issue. I don’t plan to work on this right now so please write a comment if you intend to take it. Please don’t start working without a comment so we don’t have many people solving the same problem.

If you need any help, ping me in this issue and I’ll be happy to reply or explain something.