[Enhancement] Send names of failed tests to Browserstack

[codekie]

Is your feature request related to a problem? Please describe.
No

Describe the solution you'd like
Browserstack's session-update API supports a "failed" / "passed" status and a "reason" why the session has failed.

For the time being, Nightwatch's Browsertstack-"transport module" only sends a status and an empty string as reason.

Since the test-suites (which represent a session) may include numerous tests, it can be difficult to figure out which tests exactly failed. It would be helpful to send the name of the failed tests as "reason".

Describe how the solution will work
The "testSuiteFinished"-method (in lib/testsuite/index.js) has to pass the reporter-results to the testSuiteFinished-method of the Browserstack-"transport module", which then collects the names of the failed tests and passes them as "reason" to the Browserstack's session-update request.

Describe alternatives you've considered
I didn't find any.

Additional context
The "reason" to a failed Browserstack-session:

[stale]

This issue has been automatically marked as stale because it has not had any recent activity.
If possible, please retry using the latest Nightwatch version and update the issue with any relevant details. If no further activity occurs, it will be closed. Thank you for your contribution.