Consolidate labels widget architecture

Fix tests

spec/frontend/boards/components/sidebar/board_sidebar_labels_select_spec.js

@@ -105,6 +105,7 @@ describe('~/boards/components/sidebar/board_sidebar_labels_select.vue', () => {
   describe('when labels are updated over existing labels', () => {
     const testLabelsPayload = [
       { id: 5, set: true },
+      { id: 6, set: false },
       { id: 7, set: true },
     ];
     const expectedLabels = [{ id: 5 }, { id: 7 }];

spec/frontend/vue_shared/components/sidebar/labels_select_widget/labels_select_root_spec.js

@@ -127,6 +127,6 @@ describe('LabelsSelectRoot', () => {
     createComponent({ config: { ...mockConfig, iid: undefined } });
 
     findDropdownContents().vm.$emit('setLabels', [label]);
-    expect(wrapper.emitted('updateSelectedLabels')).toEqual([[[label]]]);
+    expect(wrapper.emitted('updateSelectedLabels')).toEqual([[{ labels: [label] }]]);
   });
 });