Copy all coverage.html files into artifacts directory (#56)
Copy all coverage.html files into artifacts directory (#56)

* Copy all coverage.html files into artifacts directory

This allows archiving/inspection of coverage for all of the submodules
in opentelemetry-go-contrib.

* Fall back to tar with a file list.  cpio missing fromm docker image.

* fixup! Fall back to tar with a file list.  cpio missing fromm docker image.
open-telemetry/opentelemetry-go-contrib,open-telemetry/opentelemetry-go-contrib,open-telemetry/opentelemetry-go-contrib