MDL-71642 qbank_comment: Add question comment plugin to core

This implementation will introduce a qbank plugin
"comment" which will allow users with the capability
to comment in a question. It also implements a
callback for the question preview page to view
and add comments from the preview page. Comment
plugin is implemented using the existing comments
API from the core.

Co-Authored-By: Guillermo Gomez Arias <[email protected]>
Co-Authored-By: Safat Shahin <[email protected]>
Co-Authored-By: Matt Porritt <[email protected]>

lib/questionlib.php

@@ -387,6 +387,9 @@ function question_delete_question($questionid) {
         }
     }
 
+    // Delete question comments.
+    $DB->delete_records('comments', ['itemid' => $questionid, 'component' => 'qbank_comment',
+                                            'commentarea' => 'question']);
     // Finally delete the question record itself
     $DB->delete_records('question', array('id' => $questionid));
     question_bank::notify_question_edited($questionid);
@@ -1569,7 +1572,7 @@ function question_has_capability_on($questionorid, $cap, $notused = -1) {
 
     // These are existing questions capabilities that are set per category.
     // Each of these has a 'mine' and 'all' version that is appended to the capability name.
-    $capabilitieswithallandmine = ['edit' => 1, 'view' => 1, 'use' => 1, 'move' => 1, 'tag' => 1];
+    $capabilitieswithallandmine = ['edit' => 1, 'view' => 1, 'use' => 1, 'move' => 1, 'tag' => 1, 'comment' => 1];
 
     if (!isset($capabilitieswithallandmine[$cap])) {
         return has_capability('moodle/question:' . $cap, $context);
@@ -1742,6 +1745,8 @@ function question_get_question_capabilities() {
         'moodle/question:moveall',
         'moodle/question:tagmine',
         'moodle/question:tagall',
+        'moodle/question:commentmine',
+        'moodle/question:commentall',
     );
 }