Delegate logic of send_new_otp to user#send_new_otp_after_login?

Instead of keeping this logic nested in the Warden hook, call a method on the
user object to determine if a new OTP code should be delivered.

lib/two_factor_authentication/hooks/two_factor_authenticatable.rb

@@ -7,7 +7,7 @@ Warden::Manager.after_authentication do |user, auth, options|
 
   if user.respond_to?(:need_two_factor_authentication?) && !bypass_by_cookie
     if auth.session(options[:scope])[TwoFactorAuthentication::NEED_AUTHENTICATION] = user.need_two_factor_authentication?(auth.request)
-      user.send_new_otp unless user.totp_enabled?
+      user.send_new_otp if user.send_new_otp_after_login?
     end
   end
 end

lib/two_factor_authentication/models/two_factor_authenticatable.rb

@@ -62,6 +62,10 @@ module Devise
           send_two_factor_authentication_code(direct_otp)
         end
 
+        def send_new_otp_after_login?
+          !totp_enabled?
+        end
+
         def send_two_factor_authentication_code(code)
           raise NotImplementedError.new("No default implementation - please define in your class.")
         end