Return screenshot status with test/suite status

[aaronfay]

This adds a new option for executing a test or suite options.useScreenshotForPassingStatus.

Modified to add an additional return param to the signatures for executeTest and executeSuite:

const [result, passing, screenshotPassing] = await ghost.executeTest(...)

Also fixes a regression where a suite/test executed with a CSV containing 1 row would return a single result instead of a list.

[aaronfay]

@justinklemm yeah good call 👍🏻 that would be much cleaner.