CuPy issues in `test_ccdproc`

+ `test_subtract_overscan_model`: modeling converts to numpy array
+ `test_trim_with_wcs_alters_wcs`: wcs apparently converts to numpy also...
+ `test_unit_mismatch_behaves_as_expected`: something about `IrreducibleUnit` and `<<` operator -- this converts to numpy
+ `test_flat_correct_data_uncertainty`: Still using `np_array` in this test function
+ `test_catch_transform_wcs_warning`: same as `test_trim_with_wcs_alters_wcs`
+ `test_block_reduce`: nddata/compat converts mask to numpy array (which I guess I knew)
+ `test_block_average`: same as block_reduce
+ `test_block_replicate`: same as block_reduce
+ `test_cosmicray_median_does_not_change_input`: same as `test_trim_image_fits_section` **CHECK BECAUSE THIS SHOULD BE FIXABLE**
+ `test_cosmicray_lacosmic_does_not_change_input`: Quantity numpy conversion; also watning about copy keyword
+ `test_wcs_project_onto_same_wcs`: same as `test_trim_with_wcs_alters_wcs`
+ `test_wcs_project_onto_same_wcs_remove_headers`: same as `test_trim_with_wcs_alters_wcs`
+ `test_wcs_project_onto_shifted_wcs`: same as `test_trim_with_wcs_alters_wcs`
+ `test_wcs_project_onto_scale_wcs`: same as `test_trim_with_wcs_alters_wcs` -- comes up `wcs_for_testing`
+ `test_sigma_func_for_ccddata`: astropy stats converts to numpy array