Better support, and also document, use with IPM

[isc-tleavitt]

When used in an IPM context we should automatically determine which classes to cover (without requiring coverage.list). Documentation in this GitHub repo should cover how to enable that as well as incorporate relevant content from https://community.intersystems.com/post/unit-tests-and-test-coverage-intersystems-package-manager .

It's possible that passing the IPM context to the unit test manager could require an IPM change - likely just adding a line to pass the package name as a user param. Could also be achieved through a custom lifecycle class within this package (which we'd want to exclude).

Probably makes sense to hold this until after the IPM rename is done.

[isc-tleavitt]

This should also include conventions around unit test resource directories given the issue with coverage.list described here: intersystems/ipm#389