Finalize a registration with Webauthn using the WebAuthn API response to a navigator.credentials.create() call.
The Webauthn API uses binary data represented by ArrayBuffers for certain input/output values.
The Hanko API returns these values as base64url-encoded, so they must be converted to ArrayBuffers
when passed to the Webauthn API. Similarly, Webauthn API output must be converted to base64url-encoded values
when passed to the Hanko API (e.g. using the webauthn-json library).