Tests: add actual and expected messages to test reporter

[timmywil]

Summary

3.x version of #5443

Add the actual and expected messages to the reporter.

Also, I realized that test.errors contained all the failed assertions and test.assertions contained only passed ones, so I was able to clean up that code a bit.

Checklist

• [x] New tests have been added to show the fix or feature works
• [x] If needed, a docs issue/PR was created at https://github.com/jquery/api.jquery.com