feat: sequencer saving may be async

[FauxFaux]

Summary

Allow a TestSequencer implementation to perform async operations during its allFailedTests and cacheResults phases.

It's already allowed for sort, but not for the other methods, which I believe are part of the public/extensible API.

My Sequencer wants to go to a database.

Test plan

There's already a test for sort, and I've added a similar test for allFailedTests.

It's hard to directly test cacheResults is awaited, as it's void. We could attempt to catch it with sleeps and testing the implementation ordering; e.g. checking if it has completed before the globalHook has run? It doesn't seem to have any value.
awaiting it is necessary, as otherwise longer cacheResults implementations eventually trigger the Jest did not exit one second after the test run has completed. failure.

[SimenB]

nice, thanks!

[github-actions]

This pull request has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.
Please note this issue tracker is not a help forum. We recommend using StackOverflow or our discord channel for questions.