* 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 <[email protected]>
Co-authored-by: Elio Bischof <[email protected]>
Co-authored-by: Livio Spring <[email protected]>