feat(aio): refactors AppComponent and its kids + sidenav hiding (#15570)

-hides sidenav when current doc is not in sidenav menu
-displays top menu on the side as nodes instead of mini top menu

aio/e2e/app.e2e-spec.ts

@@ -21,9 +21,13 @@ describe('site App', function() {
 
     // navigate to a different page
     page.getLink('features').click();
+    expect(page.getDocViewerText()).toMatch(/Features/i);
 
-    // check that we can navigate to the tutorial page via a link in the navigation
-    page.getLink('tutorial').click();
+    // Show the menu; the tutorial section should be fully open from previous visit
+    page.docsMenuLink.click();
+
+    // Navigate to the tutorial introduction via a link in the sidenav
+    page.getNavItem(/introduction/i).click();
     expect(page.getDocViewerText()).toMatch(/Tutorial: Tour of Heroes/i);
   });