Load data via standard datacube load funcs

[mpaget]

The current virtual product find (bag) and load (box) methods in the Process input_data functions may be munging the CRS or other load parameters that we might expect to work for dc.load.

• Write an alternative input_data function that uses find (dc.find_datasets) and load (dc.load) funcs to build an xarray object.

This may help with dask too.