Updated SimpleSamlPHP to work without composer

- added configiguration that allows user to configure path to
SimpleSamlPHP library

config/config_defaults.inc.php

@@ -328,6 +328,7 @@ $STUDIP_AUTH_CONFIG_OAUTH2 = [
 
 $STUDIP_AUTH_CONFIG_SIMPLESAMLPHP = [
     'sp_name'           => 'default-sp',
+    'path_to_simple_saml_php' => '/var/simplesamlphp/src/_autoload.php' // path to _autoload.php of SimpleSamlPHP library
     'user_data_mapping' => [
         'auth_user_md5.Email'    => ['callback' => 'getUserData', 'map_args' => 'email'],
         'auth_user_md5.Nachname' => ['callback' => 'getUserData', 'map_args' => 'firstName'],

lib/classes/auth_plugins/StudipAuthSimpleSamlPHP.php

@@ -16,6 +16,8 @@ class StudipAuthSimpleSamlPHP extends StudipAuthSSO
     // Name of attribute that contains username (if empty it will use NameID as username)
     public ?string $username_attribute = null;
 
+    public ?string $path_to_simple_saml_php = null;
+
     public ?array $userdata = null;
     public SimpleSAML\Auth\Simple $as;
 
@@ -26,6 +28,12 @@ class StudipAuthSimpleSamlPHP extends StudipAuthSSO
     {
         parent::__construct($config);
 
+        if(!isset($this->path_to_simple_saml_php)){
+            require_once('/var/simplesamlphp/src/_autoload.php');
+        }else{
+            require_once($this->path_to_simple_saml_php );
+        }
+
         if (!isset($this->plugin_fullname)) {
             $this->plugin_fullname = _('SAML');
         }