MDL-35710 mod_assign Add submission_editable paramenter to event object

This will allow to keep assessable_submitted event object structure consistent
throughout the system, while particular modules could define own parameters
within params variable.

This module defines submission_editable parameter to reflect if user can edit
submission before assessment has been done.

mod/assign/db/events.php

@@ -49,4 +49,6 @@
     ->itemid         = // The submission id of the user submission.
     ->courseid       = // The course id of the course the assign belongs to.
     ->userid         = // The user id that the attempt belongs to.
+    ->params         = // Array of module specific parameters
+        -> submission_editable = // Whether user can edit submission before assessment has been done.
 */

mod/assign/locallib.php

@@ -3332,6 +3332,9 @@ private function process_submit_for_grading($mform) {
                 $eventdata->itemid       = $submission->id;
                 $eventdata->courseid     = $this->get_course()->id;
                 $eventdata->userid       = $USER->id;
+                $eventdata->params       = array(
+                    'submission_editable' => false,
+                );
                 events_trigger('assessable_submitted', $eventdata);
             }
         }