* Add GitHub action and pre-push hook for syncpack for react and react-dom
* Fix typo in pre-push script
* Don't execute suggested command to fix mismatches automatically.
* Update react and react-dom to 17.0.2
* Move changelog check to last, so that pre-push still fails if check isn't successful
* Add changelog files
* Correct issue with syncpack.yml referencing an internal action
* Add command to top-level package.json for fixing mismatches
* Update syncpack action to only run when package.json files are affected
* Update workflow to just run syncpack list-mismatches
* Add version pinning to syncpackrc