Unify representation of dimensions_values_labels

Currently the data model defines an alternative for the type of the field dimensions_values_labels.

The problem is that the API returns those values as it.

Example: in the result of this API call: https://api.db.nomics.world/v22/series?observations=0&series_ids=CEPII/CHELEM-TRADE-GTAP/AES.AES.CAT._NV, the values of _meta.datasets.dimensions_values_labels are mix of dicts and array:

importer is a dict => good:

product is an array => bad:

Proposed solution

The API should return a unified representation of dimensions_values_labels, not mix of dicts and arrays. But the JSON files stored in Git repositories can keep the dual representation.

TODO before closing

• amand this commit in dbnomics-python-client project