MDL-71641 qbank_tagquestion: Add Tag question plugin to core

This implementation will introduce a qbank plugin "tagquestion"
which will implement the tag question actions in the question
bank view by replacing the core class. Having this plugin
will give users the flexibility of enabling or
disabling this action.

lib/classes/plugin_manager.php

@@ -1943,6 +1943,7 @@ class core_plugin_manager {
                 'editquestion',
                 'exportquestions',
                 'importquestions',
+                'tagquestion',
                 'viewcreator',
                 'viewquestionname',
                 'viewquestiontext',