Enh: osw.core.OSW.register_model should be able to handle dataclasses typing attributes with other dataclasses

[LukasGold]

Users would expect to be able to autogenerate a JSON-Schema based on the Dataclass the have defined in Python with attributes that have been typed to other dataclasses

See the current example: https://github.com/OpenSemanticLab/osw-python/blob/main/examples/register_model.py