Vitest Pros:
* Automated failing test comments on github PRs
* A nice local UI with incremental testing when changing files (`yarn
test:ui`)
* Also nicely supported in all major IDEs, click to run test works (so
we won't miss what we had with jest).
* Works well with ESM
Vitest Cons:
* The ESBuild transformer vitest uses takes a little longer to transform
than our current SWC/jest setup, however, it is possible to setup SWC as
the transformer for vitest as well (though it only does one transform,
so we're paying ~7-10 seconds instead of ~ 2-3 seconds in transform
phase).
* Exposes how slow our tests are (tongue in cheek here)
