Fix get_transform for non-celestial WCS input that matches axes WCS

[astrofrog]

The function to check if two WCS objects have the same world coordinates may still need to change depending on discussion in https://github.com/astropy/astropy/issues/4085

Still needs:

• [ ] tests
• [ ] changelog entry

[astrofrog]

Closing this now that WCSAxes is in Astropy