Help merging a PR

[LouisDesdoigts]

Hey so I've developed a jax-based cubic-spline interpolator for the scipy.map_coordinates function (PR #14218). I suspect it will need some small tweaks to merge into the main repo and was hoping I could get someone to review it?

This in an important feature for some software I am developing and I know other users have expressed interest in this feature so was hoping to get some help pointing me to what changes are needed!

I also have a jax version of the scipy.gaussian_filter function that I will need to merge in the future too, but I'm waiting to see the process on this PR to make the next one easier.

Any help is greatly appreciated!