Display results in Github Job Summary

[rohan-at-sentry]

In the event this action is not used in the context of a pull request (i.e. a scheduled test, pre-release test, etc.), it would be nice to be able to also display the results in GitHub's Job Summary in lieu of a PR comment. We currently use https://github.com/phoenix-actions/test-reporting to do this and it works nicely. When sharing test results, permalinking to the job summary works better due to the bigger screen size it can occupy. If this feature was added, we'd switch over completely!

Originally posted by @houserx-jmcc in codecov/feedback#304 (comment)

[webknjaz]

Here's an action I'm using for this: https://github.com/test-summary/action.

[rohan-at-sentry]

@webknjaz @houserx-jmcc this is something we're just finalizing building on. I'll reach back out here once this is ready to use