WIP: react-update-imports pattern

[amedeedaboville]

The pattern comes with 17 unit tests from the react-codemod repo. Only 9/17 are passing.

The main things left are:

• figuring out when to not remove the default import. The example given is when the React variable itself is used, like Promise.resolve(React), which looks weird. I think this is saying, "is the React identifier present in a non import, non React.something way?" This is where I got stuck.
• accumulating the React symbols used to import them instead of all of React (eg changing from import React from 'react' to `import { useState, useMemo } from 'react'). I had a draft of this but didn't get to running it.
• dealing with import type React separately and not removing it.