Add option to use different reference arrays for derived test classes

[csaluski]

Previously tests could not be inherited from classes in a way that let each class save its own array. This change makes the file written use the full test name, including the class name, instead of just the test name within the class.

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This use case came up in a project I'm working on right now. The overall use case is to create a base class with tests that use class variables (It must not start with Test or Pytest will try to run its tests directly), then derive new Test classes from that class with different data. This is a normal Pytest workflow, but before this change Arraydiff would use the same name for each saved array, see the failing test case. It does not change default behavior, and adds this behavior when the "derive_classes" kwarg is added to the Arraydiff mark.

I think this change is nearly complete, but it might be worth revising the naming convention. I also notice that the Windows CI tests currently fail in a way that I haven't been able to diagnose, I'd appreciate some help figuring fixing those.

[pllim]

Thanks. I noticed that CI was disabled due to inactivity. I just re-enabled it but will have to close/reopen to trigger. Please do not be alarmed.