Utilize new built-in support for complex numbers in netCDF

[rgcoe]

I don't entirely understand all of the different packages and standards, but it appears that there's now some more built-in support within xarray for handling complex numbers in netCDF files. Here's what I've looked at so far:

• Issue in xarray noting some new functionality for netCDFs: Writing complex numbers to netCDF pydata/xarray#9246
• Guidance in xarray's docs for handling complex numbers for netCDFs: https://docs.xarray.dev/en/stable/user-guide/io.html#invalid-netcdf-files

Suggested action:

1. Confirm that using the following syntax is the preferred approach and isn't going to change any minute (it seems like you may already/soon be able to do this using engine=netcdf4): da.to_netcdf("complex.nc", engine="h5netcdf", invalid_netcdf=True)
2. Update (maybe even delete) write_netcdf and read_netcdf in core.py

[rgcoe]

This is really mostly a capytaine thing, I will create an issue there and close this one when I do.