Include package in test result

[dagood]

The package path doesn't appear in the test viewer, which is typically acceptable because tests tend to have a unique, obvious name that shows up in a simple search, but it makes results more obscure at first glance:

IMO when there are more than a handful of test failures, this makes it harder to pick out failures with unique root causes. These all share a root cause except the last one:

Maybe it's too noisy to have the package path in the top-level list, but I wanted to raise this issue to consider.

[dagood]

• Rename test outputs go-infra#445
• Include package in JUnit test names #2207