Wrap fft for dask

[lithomas1]

There's some failures relating to the expected dtype on older numpy versions.

[asmeurer]

The wrappers in common should already be handling the dtype difference. It looks like the norm keyword isn't working, though.

[lithomas1]

Going to pick this up again this week.

Thanks for not closing.

[lithomas1]

This should be ready for a look now.

Tests are passing with dask main. (this should be mergeable whenever dask cuts its next release).

[asmeurer]

Does dask still require the wrappers here? The only thing they do for NumPy is fix upcasting for 32-bit types, which has been fixed in NumPy 2.0. If the next version of dask has the NumPy 2.0 behavior then no wrapping is necessary at all.

[lithomas1]

Ah thanks, I'll go and wrap that.

Curious why it's only on fftfreq and not on fft

[lucascolley]

fftfreq creates an array from scalar inputs, so there is no device to infer.

fft takes arrays as input so can infer the device.

[lithomas1]

I think I was actually wrapping stuff incorrectly all this time (I forgot to import the wrappers in init)

I'm going to give only wrapping fftfreq/rfftfreq a shot.

[lithomas1]

@asmeurer This should be ready for a look now.

Sorry for the long delay, had to wrangle with Github Actions/the __all__ tests for a while.

[asmeurer]

This looks good, and I think the existing tests should be checking all the code that's been added here, so if tests are passing I'm reasonably confident this is all correct.