Define and document the serialization format for the columns and the data
Related to `datasets`.

Currently, `datasets` defines the columns as "features" (in the dataset-info.json file), and the values are native objects, not necessarily dicts.

We need to_dict and from_dict, both for the columns and the data.

It's what's done in https://github.com/huggingface/datasets-server/tree/main/services/worker/src/worker/models/column, but possibly this part should go to the `datasets` library.

eg. how do we serialize a Timestamp column and value? See https://github.com/huggingface/datasets-server/blob/main/services/worker/src/worker/models/column/timestamp.py for the current way we implemented in datasets-server.
Define and document the serialization format for the columns and the data: Related to `datasets`.

Currently, `datasets` defines the columns as "features" (in the dataset-info.json file), and the values are native objects, not necessarily dicts.

We need to_dict and from_dict, both for the columns and the data.

It's what's done in https://github.com/huggingface/datasets-server/tree/main/services/worker/src/worker/models/column, but possibly this part should go to the `datasets` library.

eg. how do we serialize a Timestamp column and value? See https://github.com/huggingface/datasets-server/blob/main/services/worker/src/worker/models/column/timestamp.py for the current way we implemented in datasets-server.