Setup test coverage with vitest

[siddharthkp]

Looks like we no longer create a test coverage report after migration from jest to vitest. Vitest has a good coverage guide that should help

[joshblack]

@siddharthkp what are you thinking would be the goal with test coverage? Is it just to have a better sense of our coverage or do we want a baseline setup? e.g. we should have >80% coverage or something

[siddharthkp]

Both tbh. I'd like us to have really high coverage, but no clue how far we are from that to say anything