[WIP] Upgrade to Jest 25

[trueadm]

This PR upgrades us to the latest version of Jest. Unfortunately, we run into issues doing this due to the fact newer versions of JSDOM require testURL to be http://localhost. Historically, this has been about:blank for our tests, because we depend on behavior differences in JSDOM that ensure our existing tests work as expected and changing the testURL (as I've done in this PR) now causes many of our tests to fail. As per the comment in our config.base.js by @SimenB :

  // Jest changed from `about:blank` to `http://localhost` default in 24.5 (https://github.com/facebook/jest/pull/6792)
  // in order to address https://github.com/facebook/jest/issues/6766. If one uses `about:blank` in [email protected] or
  // newer, it fails with `SecurityError: localStorage is not available for opaque origins`. However, some of React's
  // tests depend on `about:blank` being the domain (for e.g. `url` in `img` tags). So we set `about:blank` here to
  // keep the current behavior and make sure to keep the version of JSDOM to version lower than 11.12. This will have
  // to be addressed properly when Jest 25 is released, as it will come with a newer version of JSDOM.

I'm unsure as to how we can resolve this. Maybe @SimenB has some ideas?

[trueadm]

For some reason I completely missed #17896. I'll close this PR in favor of that PR.

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