Hspy distributed file reader

[CSSFrancis]

Describe the functionality you would like to see.

It should be possible to load hdf5 files using dask distributed. I think the major thing we need to do is add in the ability to pickle h5py objects.

We should be able to drop in https://github.com/DaanVanVugt/h5pickle

or write our own code for it --> https://github.com/pydata/xarray/issues/4242