Add: Ntlm plugin for auth

src/Plugin/migrate_plus/authentication/Ntlm.php

+<?php
+
+namespace Drupal\migrate_plus\Plugin\migrate_plus\authentication;
+
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\migrate_plus\AuthenticationPluginBase;
+
+/**
+ * Provides NTLM (Microsoft NTLM) authentication for the HTTP resource.
+ *
+ * @Authentication(
+ *   id = "ntlm",
+ *   title = @Translation("Ntlm")
+ * )
+ */
+class Ntlm extends AuthenticationPluginBase implements ContainerFactoryPluginInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getAuthenticationOptions() {
+    return [
+      'auth' => [
+        $this->configuration['username'],
+        $this->configuration['password'],
+        'ntlm',
+      ],
+    ];
+  }
+
+}