AARC IDP HINT implemented

lib/SimpleSAML/Auth/ExtendedAuthnRequest.php

+<?php
+
+namespace SimpleSAML\Auth;
+
+use SAML2\AuthnRequest;
+
+/**
+ * Class representing Authentication Request, aware of the AARC_IDP_HINT param
+ *
+ * @package SimpleSAMLphp\Auth
+ */
+class ExtendedAuthnRequest extends AuthnRequest
+{
+    private $aarc_idp_hint = null;
+
+    /**
+     * @return null
+     */
+    public function getAarcIdpHint()
+    {
+        return $this->aarc_idp_hint;
+    }
+
+    /**
+     * @param null $aarc_idp_hint
+     */
+    public function setAarcIdpHint($aarc_idp_hint): void
+    {
+        $this->aarc_idp_hint = $aarc_idp_hint;
+    }
+}