Improve the netcdf_to_dict function

Issue

The current function do not display many information and could be improved to generate dictionaries in function of a facets. For example, a dictionary per experiment_id.

What has been done so far

We have devised a new method to import the dictionary : based on a given facet we decompose the ensemble of entries into dictionaries for this given facet. For example, if we decompose on the experiment_id facet, if we have piClim-aer and piClim-control, that will lead to two dictionaries.

This needs to be coded as a function.