Add DiscoverTestCases operation

[rtzoeller]

• This contribution adheres to CONTRIBUTING.md.

What does this Pull Request accomplish?

Adds a new operation for discovering/enumerating test cases in a repository.

Why should this Pull Request be merged?

We need a way for the test pipeline to discover tests.

What testing has been done?

Hand testing with the LabVIEW CLI

[buckd]

Normally, I'd say you should use <National Instruments>/Shared/LabVIEW CLI/Operations/Utilities/GetOperationOutput.vi instead of creating your own return code from the error cluster, but even the built-in operations don't all use this, so it's up to you.

[buckd]

This is pretty complicated. You could just strip the path from the current VI twice to get the folder name (which matches the class name) or you could just hard code it, since the operation name isn't dynamic.

[csjall]

• The top level VI, RunOperation.vi, is too busy. Look at RunVITester.lvclass:RunOperation.vi for some clean code inspiration. Create a utility method to parse output and simply return results.

• It seems the class name terminal was used for debugging purposes. Removed unwired terminal.