MDL-72553 qbank_customfields: Add custom fields for question types

Custom fields can now be added to question types.
Site administrators can configure the custom fields and
filed types available. Teachers and question creators can
then use these fields for extra question metadata when
creating questions. Question creators can control if
the fields are displayed to students when they are
taking a quiz or not.
This features uses the core Moodle custom field API.

Co-Authored-By: Matt Porritt <[email protected]>
Co-Authored-By: Safat Shahin <[email protected]>
Co-Authored-By: Marc-Alexandre Ghaly <[email protected]>

lib/questionlib.php

@@ -377,6 +377,10 @@ function question_delete_question($questionid) {
     // Delete all tag instances.
     core_tag_tag::remove_all_item_tags('core_question', 'question', $question->id);
 
+    // Delete the custom filed data for the question.
+    $customfieldhandler = qbank_customfields\customfield\question_handler::create();
+    $customfieldhandler->delete_instance($question->id);
+
     // Now recursively delete all child questions
     if ($children = $DB->get_records('question',
             array('parent' => $questionid), '', 'id, qtype')) {