* feat: add otp name and make it configurable
* feat: use pre-existing otp env var
* feat: use requested domain if otp issuer is empty
* cleanup
---------
Co-authored-by: Sem den Broeder <semnelldenbroeder@gmail.com>
Co-authored-by: Elio Bischof <eliobischof@gmail.com>
Co-authored-by: Livio Spring <livio.a@gmail.com>