chore: add @testing-library/jest-dom, update related deps

- Note: using `npm install --save-dev` will also sort dependencies
automatically.

add:

- @testing-library/jest-dom
  - Need to import in test/helpers.js:
    https://github.com/testing-library/jest-dom#installation
  - Need to use `setupFilesAfterEnv` instead:
    testing-library/jest-dom#122

update:

- axe-core
- jest, @types/jest
  - When upgrading to v27, we need to explicitly specify jsdom env:
    https://jestjs.io/blog/2021/05/25/jest-27#flipping-defaults
- @testing-library/react
- @testing-library/react-hooks
- @testing-library/user-event

squash