title: Multiple authentication methods for a user in Keycloak
body: <p>I would like to let my users have a choice which authentication method to use. For example, they could be presented with a menu to pick an option (username/pass, username/pass+OTP, etc).
  Then, Keycloak should, based on their choice, assign specific scope to the token.</p>
  
  <p>Is this possible to do with Keycloak (probably by somehow utilizing auth methods chaining) and how? I couldn’t find this in the documentation but it seems as a reasonable use-case to me.</p>