Convert to parallel code using xarray and Dask

[DaniJonesOcean]

I'd like to convert this code:

https://github.com/so-wise/ERA5/blob/main/regrid_xesmf.py

To a version that uses xarray and Dask to speed up processing and to take advantage of xarray's nice properties. Specifically, I'd like to be able to do something like what is shown here:

https://xesmf.readthedocs.io/en/latest/notebooks/Dask.html

I have tried, but I have not been able to get this to work. Note that you'll need to download some ERA5 subset files in the first place:

https://github.com/so-wise/ERA5/blob/main/main_get_era5.py