MDL-71573 qbank_exportquestion: Add plugin to core

This implementation will introduce a qbank plugin "exporquestions"
which will add the export feature in the question bank view
by replacing the core classes. Having this plugin will give users
the flexibility of enabling or disabling the export questions tab.

Co-Authored-By: Guillermo Gomez Arias <[email protected]>

lib/classes/plugin_manager.php

@@ -1939,7 +1939,7 @@ class core_plugin_manager {
             ),
 
             'qbank' => [
-                'deletequestion',
+                'deletequestion', 'exportquestions',
             ],
 
             'qbehaviour' => array(