CustomEffectCx: Fixed pitch not being passed.

CustomEffectCx: Fixed in-place mode.
FileUtilities: File name taken from CallerMemberNameAttribute by default.
CustomFiltersCxTests, CustomEffectsCxTests, EffectGroupCxTests: Using real images.

FileUtilities: Renamed to ImageResults, and made to run more in parallel with the unit tests. Test methods don't need to await the saving.
KnownImages: Fixed wrong size for one image.