* 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
The pre-push hook uses sh but contained syntax that is only supported by
bash. `=` in sh should be used instead of `==` to check for string
equality. Before this change, we were getting the following error when
pushing to any branch:
```
git push
husky > pre-push (node v10.22.1)
./bin/pre-push.sh: 7: [: refs/heads/master: unexpected operator
```
This error didn't block the push, but meant that the message asking
developers to confirm if they wanted to push to master was never
displayed. This problem was introduced in commit
8c25557bf5 added in PR #27028.
Sam Seay
jonathansadowski
Roy Ho
Chi-Hsuan Huang
Paul Sealock
Claudio Sanches
Rodrigo Primo
Peter Fabian