Add coverage testing

[brahyt-sf]

You can run testing with yarn coverage

[1]   110 passing (25s)
[1]   3 pending
[1]
[1] mocha exited with code 0
--> Sending SIGTERM to other processes..
[0] wiremock exited with code SIGTERM

=============================== Coverage summary ===============================
Statements   : 93.75% ( 360/384 )
Branches     : 82.29% ( 79/96 )
Functions    : 100% ( 114/114 )
Lines        : 93.66% ( 355/379 )
================================================================================
✨  Done in 28.23s.

[ekozilforce]

Needs a npm run format:write to get past the format check in ci

[brahyt-sf]

yarn test:coverage

[ekozilforce]

If macos isn't working due to the java heap running out of memory and we don't have a path to fix, we could remove it from the os matrix temporarily.

[brahyt-sf]

can do.

[ekozilforce]

I think this is a great improvement and this should close out multiple items on DoD.

I want to get this merged so we can get faster feedback as we make code changes, but we should circle back and get macos running in our test matrix before GA ideally.