Move wisski instance code to separate package

internal/wisski/php/settings.php

@@ -0,0 +1,29 @@
+<?php
+
+/** gets a setting from 'settings.php' */
+function get_setting($name) {
+    use \Drupal\Core\Site\Settings;
+    return Settings::get($name);
+}
+
+/** sets a setting in 'settings.php' */
+function set_setting($name, $value) {
+    // load install.inc
+    if(is_file(DRUPAL_ROOT . "/internal/")) {
+        include_once DRUPAL_ROOT . "/internal/core/includes/install.inc";
+    } else {
+        include_once DRUPAL_ROOT . "/core/includes/install.inc";
+    }
+    
+    // update the provided setting
+    $settings["settings"][$name] = (object)[
+        "value" => $value,
+        "required" => TRUE,
+    ];
+
+    // find the filename
+    $filename = DRUPAL_ROOT . "/" . \Drupal::service("site.path") . "/settings.php";
+    drupal_rewrite_settings($settings, $filename);
+
+    return True;
+}