Move data generated by `MoveTestDataSet` to VTK data files

Kenneth Morelandrequested to merge
kmorel/vtk-m:testing-data-files into master

he MoveTestDataSet predates the ability to load VTK data files as well as the testing conventions for loading data files from the vtk-m/data directory. This method of creating data is a bit silly now, so instead add small data files to the VTK-m repo that can be loaded by the testing framework.

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