MDL-71575 qbank_viewquestiontext: Add View question text plugin to core

This implementation will introduce a qbank plugin "viewquestiontext"
which will view the question text row in the question bank view
by replacing the core class. Having this plugin will give users
the flexibility of enabling or disabling the question text row
in the question view.

lib/classes/plugin_manager.php

@@ -1943,6 +1943,7 @@ class core_plugin_manager {
                 'editquestion',
                 'exportquestions',
                 'importquestions',
+                'viewquestiontext'
             ],
 
             'qbehaviour' => array(