ProbeAsync method in TestAgent should return collection of failures

[adydecki]

Currently, the ProbeAsync method in the TestAgent class returns a bool value indicating whether a collection of test components passes or fails. However, this does not provide enough information about the cause and nature of the failures. It would be more useful to return a collection of failures that contains the error messages and other relevant details for each failed test component. This would allow the user to easily identify and debug the failures, as well as to generate more informative reports and logs.

The proposed change is to modify the signature and implementation of the ProbeAsync method to return a Task<IEnumerable<Failure>> instead of a Task<bool>. The Failure class is a simple data structure that holds the error message and other properties of a failed test component. The ProbeAsync method should build TestSession and get the failures from there.

The change would require updating the callers of the ProbeAsync method to handle the new return type and process the failures accordingly. It would also require updating the unit tests and documentation for the ProbeAsync method.