MDL-81767 courseformat: Add module quickcreation feature

- Add new 'FEATURE_QUICKCREATE' plugin feature that indicates the module can
  be created with a single click. It will use its own 'quickcreatename' defined
  string as the initial default name.
- Add new 'core_courseformat\external\create_module' web service to create new
  modules with the quickcreate featuer in the course page.
- Add a new 'create_module' state action.

lib/moodlelib.php

@@ -500,6 +500,8 @@ define('MOD_PURPOSE_OTHER', 'other');
 */
 define('MOD_PURPOSE_INTERFACE', 'interface');
 
+/** True if module can be quickly created without filling a previous form. */
+define('FEATURE_QUICKCREATE', 'quickcreate');
 /**
  * Security token used for allowing access
  * from external application such as web services.