MDL-58575 core_calendar: Properly restrict groups in event vault

Previously we were not filtering on groups in the event vault
which meant events for all groups would be returned regardless
of which user was passed in.

This resulted in situations where one student would group overrides
for groups they were not in.

calendar/classes/local/event/data_access/event_vault.php

@@ -197,6 +197,16 @@ public function get_action_events_by_timesort(
         event_interface $afterevent = null,
         $limitnum = 20
     ) {
+        $courseids = array_map(function($course) {
+            return $course->id;
+        }, enrol_get_all_users_courses($user->id));
+
+        $groupids = array_reduce($courseids, function($carry, $courseid) use ($user) {
+            $groupings = groups_get_user_groups($courseid, $user->id);
+            // Grouping 0 is all groups.
+            return array_merge($carry, $groupings[0]);
+        }, []);
+
         return $this->get_events(
             null,
             null,
@@ -207,8 +217,8 @@ public function get_action_events_by_timesort(
             $limitnum,
             CALENDAR_EVENT_TYPE_ACTION,
             [$user->id],
-            null,
-            null,
+            $groupids ? $groupids : null,
+            $courseids ? $courseids : null,
             true,
             true,
             function ($event) {
@@ -225,6 +235,7 @@ public function get_action_events_by_course(
         event_interface $afterevent = null,
         $limitnum = 20
     ) {
+        $groupings = groups_get_user_groups($course->id, $user->id);
         return array_values(
             $this->get_events(
                 null,
@@ -236,7 +247,7 @@ public function get_action_events_by_course(
                 $limitnum,
                 CALENDAR_EVENT_TYPE_ACTION,
                 [$user->id],
-                null,
+                $groupings[0] ? $groupings[0] : null,
                 [$course->id],
                 true,
                 true,