[Notebook] new entries on brand new notebook not rendered (#3496)

* [Notebook] new entries on brand new notebook not rendered #3488

* Refactored code to 'mutateObject'  from one place only, add page to newly created section immediately,  update entries copy then call mutate to update it inside domainObject.

Co-authored-by: Jamie V <jamie.j.vigliotta@nasa.gov>
Co-authored-by: Andrew Henry <akhenry@gmail.com>

src/ui/components/ObjectLabel.vue

@@ -18,7 +18,9 @@
               title="This item is missing"
         ></span>
     </div>
-    <div class="c-tree__item__name c-object-label__name">
+    <div class="c-tree__item__name c-object-label__name"
+         :class="classList"
+    >
         {{ observedObject.name }}
     </div>
 </a>