Install React, ReactDOM and React-Scripts at the same time

Created by: n3tr

to fixes #1239 (closed)

Current Scenario

• create-react-app my-app will invokes create-react-app/index to create app folder, package.json and install react-scripts as devDependencies (--save-dev). (Use latest version if not specific).
• Use react-scripts to init project and install react and react-dom as dependencies (--save)

New

• create-react-app/index create app folder, package.json, and install react, react-dom, and react-scripts as a dependencies (--save) at the same time.
• Since react-scripts should be in devDependencies, we modify the package.json to move it to devDependencies.
• Use react-scripts to init project and check if there're react and react-dom have been installed yet. If no react and react-dom inside node_modules, install them. (this would happen when user use old CRA to create project and receive the latest version of react-scripts)

This should backward compatible with old version of CRA, in case user use previous version of CRA which won't install react and react-dom along with react-scripts.

Test plans

Both new version

• Test Scenario: Use new create-react-app with react-scripts
• Expected result:
  • Install react, react-dom, and react-scripts at the same time (by CRA)

Old CRA + new react-scripts

• Test Scenario: Use old create-react-app with new react-scripts
• Expected result:
  • Install react-scripts by CRA then install react and react-dom by react-scripts

New CRA + old version of react-scripts

• Test Scenario: Use new create-react-app with old react-scripts
• Expected result:
  • Install react, react-dom, and react-scripts by CRA.
  • And install react and react-dom again by react-scripts.