FidoAuthenticator::MakeCredential and ::GetAssertion currently take CTAP2-level request messages which carry only a subset of the information that the WebAuthn request has (e.g. uv is a bool in CTAP2, and an enum in the WebAuthn authenticator model). 

We should pass the WebAuthn-level request options instead, and do the lossy CTAP2 conversion only inside FidoAuthenticator specializations to better accommodate non-CTAP authenticators.