MDL-72125 testing: Make global $CFG available when including generators

This will remove the requirement to add the global $CFG call to the top
of generator scripts.

lib/testing/generator/data_generator.php

@@ -103,6 +103,9 @@ public function reset() {
      * @return component_generator_base or rather an instance of the appropriate subclass.
      */
     public function get_plugin_generator($component) {
+        // Note: This global is included so that generator have access to it.
+        // CFG is widely used in require statements.
+        global $CFG;
         list($type, $plugin) = core_component::normalize_component($component);
         $cleancomponent = $type . '_' . $plugin;
         if ($cleancomponent != $component) {