Code coverage variants/tasks have been drastically pruned down for sake of stability. No reporting service is being used now (between vendors), but we want to keep the local workflows from rotting. This change adds 2 artifacts with unittests:

• Bazel Code Coverage Summary: a text based formatted table of file coverage and a summary
• Bazel Code Coverage Report (lcov): a tar-zip of bazel's lcov output

These won't fail if coverage was zero, but will provide evidence of what coverage was collected, something we're completely missing now.

There is still dead code from prior gcov/coveralls paths but that can be torn down independently.