allow for different configurations based on framework choice of calling application

[jeanetteclark]

currently registering the OAuth client is specific to the authlib flask integration.

    oauth.register(
        name="vegbank_oidc",
        client_id=secrets.get("client_id"),
        client_secret=secrets.get("client_secret"),
        server_metadata_url=secrets.get("server_metadata_url"),
        client_kwargs={"scope": scope_request},
    )

We should allow for multiple integrations so that the calling application can use whatever API framework they want.

At a minimum we need to add FastAPI to support ogdc-runner, and continue support of Flask for vegbank

[mbjones]

I'll note that all of those parameters are needed for OIDC, so really the main difference is which authlib class gets imported to create the oauth object. Maybe that is simply a config option or parameter for the lib - it might not even need separate classes. Can we generate a list of all of the flask/fastapi-specific classes we would need? if its only which OAuth subclass then this might be pretty easy as a config item.

[jeanetteclark]

from authlib it is only OAuth. but note some other flask dependencies documented in issue #4