Bring the metadata endpoint into the MR Notes app

app/assets/javascripts/mr_notes/init_notes.js

@@ -25,6 +25,9 @@ export default () => {
 
       return {
         noteableData,
+        endpoints: {
+          metadata: notesDataset.endpointMetadata,
+        },
         currentUserData: JSON.parse(notesDataset.currentUserData),
         notesData: JSON.parse(notesDataset.notesData),
         helpPagePath: notesDataset.helpPagePath,
@@ -54,6 +57,7 @@ export default () => {
     },
     created() {
       this.setActiveTab(window.mrTabs.getCurrentAction());
+      this.setEndpoints(this.endpoints);
     },
     mounted() {
       this.notesCountBadge = $('.issuable-details').find('.notes-tab .badge');
@@ -65,7 +69,7 @@ export default () => {
       window.mrTabs.eventHub.$off('MergeRequestTabChange', this.setActiveTab);
     },
     methods: {
-      ...mapActions(['setActiveTab']),
+      ...mapActions(['setActiveTab', 'setEndpoints']),
       updateDiscussionTabCounter() {
         this.notesCountBadge.text(this.discussionTabCounter);
       },

app/views/projects/merge_requests/show.html.haml

@@ -63,6 +63,7 @@
                 - add_page_startup_api_call widget_project_json_merge_request_path(@project, @merge_request, format: :json)
                 - add_page_startup_api_call cached_widget_project_json_merge_request_path(@project, @merge_request, format: :json)
               #js-vue-mr-discussions{ data: { notes_data: notes_data(@merge_request, Feature.enabled?(:paginated_notes, @project)).to_json,
+                endpoint_metadata: @endpoint_metadata_url,
                 noteable_data: serialize_issuable(@merge_request, serializer: 'noteable'),
                 noteable_type: 'MergeRequest',
                 target_type: 'merge_request',