Support OIDC client authorization_parameters #168

[m-mohr]

Adds suppot for the authorization_parameters as intrdocued in openEO API v1.3.0

[flahn]

I was wondering if the standalone function login() also needs to be adapted if a user wants to overwrite the authorization_parameters. Currently there is also the parameter "config" where I allowed to pass on "client_credentials", where some parameters could also be added. Unless, of course, the authorization_parameters are always shipped with the client description from the openEO API and the user usually never need to know about those configuration.

Otherwise it should work and looks fine. To recap, the authorization_parameters are passed as they are stated during the negotiation with OIDC provider.

[m-mohr]

Thank you for the review @flahn!

So the authorization parameters will be attached to the authorization request that the client sends towards the OIDC identity provider. The parameters are a relatively rare use case, currently needed by Google and EGI check-in, which both set a single parameter that is known to the backend and they have to expose that via GET /credentials/oidc. It would be pretty bad UX to ask the user to set these parameters manually through the client, so I'd say unless we find a specific usecase from a backend, it is not needed to adapt the login method.