Jest tests are slow to run

[benhoneywill]

The jest tests are slow to run because they all access the database, so have to be run one after the other.

If we could figure out a nice way (maybe using postgresql schemas) to give each test its own database they could be run in parallel which should drastically speed up the CI job for the tests.

Relevant discussion blitz-js/blitz#2535

[benhoneywill]

Could also do something like this:

https://imhoff.blog/posts/parallelizing-jest-with-github-actions