ENH: Increase coverage for ImageStatistics module classes

[jhlegarreta]

• ENH: Increase coverage for ImageStatistics module classes
• BUG: Fix superclass name in itkTypeMacro

PR Checklist

• No API changes were made (or the changes have been approved)
• No major design changes were made (or the changes have been approved)

[jhlegarreta]

Only these few classes are included because all but itk::LabelOverlapMeasuresImageFilter inherit from ImageSink, but their RTTI has ImageToImageFilter as the superclass, so the the tests should catch the failure.

The only classes in the module that inherit from ImageSink are itk::LabelStatisticsImageFilter, itk::MinimumMaximumImageFilter, and itk::StatisticsImageFilter. Comment in the ITKv5 migration guide:
https://github.com/InsightSoftwareConsortium/ITK/pull/855/files#diff-2d43eb1ac60257c6bda5c589f292ac05fb0c13b7674aae9fd3ae6fe331b45efbR411

git blame points to this commit when looking at when the inheritance changed:
0efe8db
fdccea4
cbaddfa

Once the failure is demonstrated in CI builds, I will add a commit to fix the RTTIs.

[jhlegarreta]

134b46d was succeeding because I anticipated to the error and provided the right superclass name, and also now I realize that itkTypeMacro in reality does not do anything with the superclass parameter itself, but rather omits the virtual specifier when providing GetNameOfClass.

86deecf should fail when checking the superclass names for itk::LabelStatisticsImageFilter, itk::MinimumMaximumImageFilter, and itk::StatisticsImageFilter.

[jhlegarreta]

So the Windows build failed as expected:
https://open.cdash.org/viewTest.php?onlyfailed&buildid=7643234

Not sure why Linux and macOS did not fail, but I'm pushing the fix.