Add junit Jest reporter

[pdehaan]

References:

Jira: MNTOR-
Figma:

Description

Early work on adding JUnit XML reports for the Jest unit tests. Eventually we'll want to ingest these into a pipeline to track tests and test performance over time (which means working on getting these stored as artifacts in the GitHub Actions pipeline too).

Screenshot (if applicable)

Not applicable.

How to test

Run tests locally, look for a root /jest-junit.xml file.

Checklist (Definition of Done)

• Localization strings (if needed) have been added.
• Commits in this PR are minimal and have descriptive commit messages.
• I've added or updated the relevant sections in readme and/or code comments
• I've added a unit test to test for potential regressions of this bug.
• If this PR implements a feature flag or experimentation, the Ship Behind Feature Flag status in Jira has been set
• Product Owner accepted the User Story (demo of functionality completed) or waived the privilege.
• All acceptance criteria are met.
• Jira ticket has been updated (if needed) to match changes made during the development process.
• Jira ticket has been updated (if needed) with suggestions for QA when this PR is deployed to stage.

[github-actions]

Preview URL 🚀 : https://blurts-server-pr-4796-mgjlpikfea-uk.a.run.app

[Vinnl]

I believe on Relay we use coveralls.io, maybe we want to use that here too, to save the effort of setting up a full pipeline?

[Vinnl]

I think this is the one that generates the HTML report that I use to check if there's any code I forgot to write tests for:

Suggested change

	// "lcov",
	"lcov",

[rhelmer]

@pdehaan are you still working on this one?

[Vinnl]

I'm assuming no, so closing for now :)