Allow 2FA for SAML and LDAP users (#4000)

* inline totp image as data uri to prevent caching issues
* allow 2fa for ldap and saml users
* allow 2FA access for super admin to all profiles

src/Voter/UserVoter.php

@@ -83,9 +83,8 @@ final class UserVoter extends Voter
         }
 
         if ($attribute === '2fa') {
-            // two factor only works for internal users and
-            // can only be activated by the logged-in user for himself
-            return $subject->isInternalUser() && $subject->getId() === $user->getId();
+            // can only be activated by the logged-in user for himself or by a super-admin
+            return $subject->getId() === $user->getId() || $user->isSuperAdmin();
         }
 
         $permission = $attribute;