feat(fetch-router): add Node.js demo

[brookslybrand]

Simplified version of #10844

Demonstrates basic setup of fetch-router

• server.ts -- createRequestListener from @remix-run/node-fetch-server to listen to requests and call router.fetch
• routes.ts -- route definitions, leverages formAction and resources for simple CRUD routes
• router.ts -- sets up middleware and route handlers for routes defined in routes.ts

fetch-router-demo.yafw.balanced.mp4

[mjackson]

Looks good to me! Thanks, @brookslybrand 🙏