Use built-in Next layout support + lazy load

Instead of doing manual layout switching use the Nextjs nested layout
support. Also add some additional lazy loading of components. This is to
work on performance score re: #2167.

web/pages/index.tsx

@@ -1,5 +1,9 @@
+import { ReactElement } from 'react';
 import { Main } from '../components/layouts/Main';
 
 export default function Home() {
   return <Main />;
 }
+Home.getLayout = function getLayout(page: ReactElement) {
+  return page;
+};