Support email login via REST

Use UserAuthInterface->authenticate() instead of loading by username with UserStorageInterface->loadByProperties() so that email login can be used.

src/Controller/TfaUserAuthenticationController.php

@@ -110,12 +110,11 @@ final class TfaUserAuthenticationController extends UserAuthenticationController
       throw new BadRequestHttpException('Missing credentials.name.');
     }
 
-    /** @var \Drupal\user\UserInterface[] $users */
-    $users = $this->userStorage->loadByProperties(['name' => $credentials['name']]);
-
-    if (count($users) !== 1) {
+    $uid = $this->userAuth->authenticate($credentials['name'], $credentials['pass']);
+    if ($uid === false) {
       throw new BadRequestHttpException('Sorry, unrecognized username or password.');
     }
+    $users = $this->userStorage->loadByProperties(['uid' => $uid]);
 
     $this->setUser(reset($users));