The old version of prettier we were using didn't support the Flow syntax
to access properties in a type using `SomeType['prop']`. This updates
`prettier` and `rollup-plugin-prettier` to the latest versions.
I added the prettier config `arrowParens: "avoid"` to reduce the diff
size as the default has changed in Prettier 2.0. The largest amount of
changes comes from function expressions now having a space. This doesn't
have an option to preserve the old behavior, so we have to update this.
`string.replaceAll` doesn't exist in our CircleCI Docker environment. We also don't need it in this case because `semver.satisfies` allows for whitespace when specifying a range. This PR removes the unnecessary call.
In DevTools tests, if the REACT_VERSION specified, we know this is a regression test (testing older React Versions). Because a lot of tests test the DevTools front end and we don't want to run them in the regression test scenario, we decided to only run tests that have the // @reactVersion pragma defined.
Because if there are no tests specified, jest will fail, we also opt to use jest.skip to skip all the tests that we don't want to run for a specific React version istead.
This PR makes this change.
