Defines 4 new types:
* Return type of `useState()`, which has properties "0" and "1" to allow us to
infer the types when destructuring
* Type of useState() set state function
* Return type of `useRef()` so we know what is a ref
* Type of ref.current, so we know what is a ref *value*
Example:
<img width="1670" alt="Screenshot 2023-05-24 at 9 59 37 AM"
src="https://github.com/facebook/react-forget/assets/6425824/3ee7d04a-fda3-4b7b-89b7-d205d9a6fd0d">