Collect test coverage from e2e tests

[crenshaw-dev]

Summary

Today we only collect coverage from unit tests. We should also collect coverage from e2e tests.

Motivation

It would be helpful to get a clearer idea of our complete coverage.

Proposal

New go versions support collecting coverage from running code. We could collect profiles from each of the components and merge them all with the unit coverage data. https://tip.golang.org/doc/go1.20#cover

[crenshaw-dev]

Looks like combining the outputs of the various tests won't be prohibitively difficult. https://dustinspecker.com/posts/go-combined-unit-integration-code-coverage/