Improve `checkSparkAnswer` methods to allow for validation of expected results

### What is the problem the feature request solves?

When writing tests using `checkSparkAnswerAndOperator`, the testing API doesn't provide a convenient way to verify that the query actually produces the ~correct~ expected results, or any results at all.

I would like to improve the API to make it easy to improve our tests to verify results above and beyond just making sure that Comet and Spark produced the same results.

### Describe the potential solution

_No response_

### Additional context

_No response_

No file or test path is provided; begin by locating the checkSparkAnswer and checkSparkAnswerAndOperator definitions and their current call sites in the testing API. Done means tests can conveniently validate expected query results, including whether results exist, in addition to comparing Comet and Spark.

Written by the indexing model from the issue text.