dillon1000/react

Upgrade useSyncExternalStore to alpha channel (#22662)

* Move useSyncExternalStore shim to a nested entrypoint

Also renames `useSyncExternalStoreExtra` to
`useSyncExternalStoreWithSelector`.

- 'use-sync-external-store/shim' -> A shim for `useSyncExternalStore`
  that works in React 16 and 17 (any release that supports hooks). The
  module will first check if the built-in React API exists, before
  falling back to the shim.
- 'use-sync-external-store/with-selector' -> An extended version of
  `useSyncExternalStore` that also supports `selector` and `isEqual`
  options. It does _not_ shim `use-sync-external-store`; it composes the
  built-in React API. **Use this if you only support 18+.**
- 'use-sync-external-store/shim/with-selector' -> Same API, but it
  composes `use-sync-external-store/shim` instead. **Use this for
  compatibility with 16 and 17.**
- 'use-sync-external-store' -> Re-exports React's built-in API. Not
  meant to be used. It will warn and direct users to either the shim or
  the built-in API.

* Upgrade useSyncExternalStore to alpha channel