MDL-35078 enrol: allow times to be chose on bulk enrolment forms

Previously only a date was available, which made it ambigious whether
the the enrolment was inclusive of the date. Now we use a time to make
it less ambigious.

This matches changes done in other forms in MDL-41173.

enrol/bulkchange_forms.php

@@ -44,8 +44,8 @@ protected function definition() {
         $statusoptions = $this->get_status_options();
         $form->addElement('html', $this->get_users_table($users, $statusoptions));
         $form->addElement('select', 'status', get_string('alterstatus', 'enrol_manual'), $statusoptions, array('optional' => true));
-        $form->addElement('date_selector', 'timestart', get_string('altertimestart', 'enrol_manual'), array('optional' => true));
-        $form->addElement('date_selector', 'timeend', get_string('altertimeend', 'enrol_manual'), array('optional' => true));
+        $form->addElement('date_time_selector', 'timestart', get_string('altertimestart', 'enrol_manual'), array('optional' => true));
+        $form->addElement('date_time_selector', 'timeend', get_string('altertimeend', 'enrol_manual'), array('optional' => true));
 
         $this->add_action_buttons();
     }