title: Reports for Flutter test_driver execution
body: <p>I need to generate a report about how much tests was executed, how much failed, why test was failed. Is there some option to do it with <code>test_driver</code>?<br>
  We can generate json report for flutter unit tests with command <code>flutter test --machine</code>. Is there something same for <code>flutter drive</code>?</p>