Initiate the authentication of a Passkey or WebAuthn registration.
To optimize for Passkeys, set the return_passkey_credential_options field to true.
After calling this endpoint, the browser will need to call navigator.credentials.get() with the data from public_key_credential_request_options passed to the navigator.credentials.get() request via the public key argument. We recommend using the get() wrapper provided by the webauthn-json library.
If you are not using the webauthn-json library, the public_key_credential_request_options will need to be converted to a suitable public key by unmarshalling the JSON and converting some the fields to array buffers.