better badges for empty/loading model library folders (#953)

* better badges for empty/loading model library folders

for #945

* fix total count on loaded nodes

* fix test break

* additional test fix

* use a null prop fallback instead of having to explicitly calc

* patch

src/components/common/__tests__/TreeExplorerTreeNode.spec.ts

@@ -56,7 +56,7 @@ describe('TreeExplorerTreeNode', () => {
     expect(wrapper.findComponent(EditableText).props('modelValue')).toBe(
       'Test Node'
     )
-    expect(wrapper.findComponent(Badge).props()['value']).toBe(3)
+    expect(wrapper.findComponent(Badge).props()['value'].toString()).toBe('3')
   })
 
   it('makes node label editable when renamingEditingNode matches', async () => {