test typescript code coverage using jest

[aldousalvarez]

Pull Request Requirements

• Rebased onto upstream/main branch and squashed into single commit to help maintainers review it more efficient and to avoid spaghetti git commit graphs that obfuscate which commit did exactly what change, when and, why.
• Have git sign off at the end of commit message to avoid being marked red. You can add -s flag when using git commit command. You may refer to this link for more information.
• Follow the Commit Linting specification. You may refer to this link for more information.

Character Limit

• Pull Request Title and Commit Subject must not exceed 72 characters (including spaces and special characters).
• Commit Message per line must not exceed 80 characters (including spaces and special characters).

A Must Read for Beginners
For rebasing and squashing, here's a must read guide for beginners.

[petermetz]

@aldousalvarez Not bad. You can build on this towards the end solution. Things to keep in mind:

1. separate jobs will have to share their code coverage outputs somehow via the GitHub action cache or via the artifact store (whichever is a better fit - to be investigated)
2. We can't re-run the entire test suite just to obtain coverage data so this has to be done in a way that is integrated with the current test execution as-is.