Develop gridded metadata standard with Epimorphics

[mattjbr123]

Following on from this work: NERC-CEH/fdri-discovery#50

First step is to:

• Provide Epimorphics with metadata from the netcdf and Zarr versions of the datasets we have worked with on the gridded product so far
• Provide provenance information, i.e.: "these netcdf files make up this Zarr dataset"