The ESLint config has been updated to v8. The breaking changes are:
* The Prettier rule `quoteProps` has been changed from `consistent` to
`as-needed`, meaning that if one key requires quoting, only that key is
quoted rather than all keys.
* The ESLint rule `no-shadow` has been made more strict. It now
prevents globals from being shadowed as well.
Most of these changes were applied with `yarn lint:fix`. Only the
shadowing changes required manual fixing (shadowing variable names were
either replaced with destructuring or renamed).
The dependency `globalThis` was added to the list of dynamic
dependencies in the build system, where it should have been already.
This was causing `depcheck` to fail because the new lint rules required
removing the one place where `globalThis` had been erroneously imported
previously.
A rule requiring a newline between multiline blocks and expressions has
been disabled temporarily to make this PR smaller and to avoid
introducing conflicts with other PRs.
* Jestify migrations/
* Lint exclude migrations from mocha config, and add inclusion to jest config
* Add migration tests to jest config
* Exclude/ignore migration tests
* Set process.env.IN_TEST to true when running tests locally
