MDL-70165 course: always import inplace editable module.

It's required on the course participants table for the roles/groups
columns, but isn't always loaded after adding the first participant.

user/amd/src/participants.js

@@ -32,6 +32,7 @@ import Notification from 'core/notification';
 import Pending from 'core/pending';
 import jQuery from 'jquery';
 import {showAddNote, showSendMessage} from 'core_user/local/participants/bulkactions';
+import 'core/inplace_editable';
 
 const Selectors = {
     bulkActionSelect: "#formactionid",