Server-side debugging app

Application that renders all components on the server and hydrates them on the client. Common tasks:

• Run pnpm universal-app to start a local server. Does not support live reload
• To inspect the server-side-generated HTML, run pnpm universal-app, visit the local server and use either the dev tools or "View source" to see the index.html provided by the server.
• To test if all components would render on the server, run pnpm bazel test src/universal-app:prerender_test.