Fix indexing errors, add tests

[melanieclarke]

In testing your changes, I found a couple issues with array handling when combined with the multi-int case and fixed them here:

• data_shape needs to be a list, since a tuple can't be updated after creation
• data_overlap needs to get the same dtype as the input data
• indexing into the overlap array was not working correctly for 3D data, causing a crash when there was a spatial size difference in the rateints files (this issue predates your changes).

I also added some unit tests that I think should cover the various cases of allowed data and background spatial and integration size differences.

Testing the regression test created for spacetelescope#8326 locally, this version passes with no differences in the output FITS files.

[thomaswilliamsastro]

Great, that looks good to me. I've merged, rebased onto main, and pushed