refactor(ivy): Update query-related comments (#29342)

Just updating comments in query-related things to make it easier for the next person that has to grok this for the first time.

Also adds a demo from @mhevery to one of the query specs

Related #29031

PR Close #29342

packages/core/test/render3/query_spec.ts

@@ -1603,6 +1603,7 @@ describe('query', () => {
          });
 
       // https://stackblitz.com/edit/angular-7vvo9j?file=src%2Fapp%2Fapp.component.ts
+      // https://stackblitz.com/edit/angular-xzwp6n
       it('should report results when the same TemplateRef is inserted into different ViewContainerRefs',
          () => {
            let tpl: TemplateRef<{}>;