Potential Auth models

[rhysrevans3]

My understanding of the transaction api's authroisation code is:

• The authorizer collects information about the user and adds it to the request state.
• The client then calls its authorize method which check the incoming payload against the generated authorisation state.

This pull request adds a pydantic model for the return of the authorizer. If the East and West authorizer middleware returns the same model it would allow us to use the same authorize method in the client.

Any objections to having a model for the return of the authorizer? Or to the structure or content of the model?

[sturoscy-personal]

Apologies if I'm missing something, isn't this already taken care of by the RequesterData and Auth models? https://github.com/ESGF/esgf-playground-utils/blob/main/esgf_playground_utils/models/kafka.py#L90-L100

[sturoscy-personal]

Perhaps a better question to ask is where would these models be used in the transaction api?