Convert `custom-server-express` example to TypeScript

[maxproske]

Converted Express example to TypeScript to match Contribution docs.

• Added nodemon to match the custom-server example, and allow live reloading of server.ts
• Updated README with explainer for non-standard <Link href="/a" as="/b"> routing

Documentation / Examples

• [X] Make sure the linting passes by running pnpm build && pnpm lint
• [X] The "examples guidelines" are followed from our contributing doc

[imranbarbhuiya]

https://github.com/vercel/next.js/pull/33128#issuecomment-1009456136

[maxproske]

#33128 (comment)

Thanks for the link! Though I think this example should be maintained as long as it's referenced by the Next.js custom server docs.

[maxproske]

@leerob What do you think we should do with the following JavaScript examples?

I think they should be maintained and converted to TypeScript, however based on your comment #33128 (comment), it sounds like custom servers aren't recommended, and therefore the examples can't be updated. If this is the case, it might make sense to deprecate them in favour of the main custom-server example?

• custom-server-actionhero
• custom-server-express
• custom-server-fastify
• custom-server-hapi
• custom-server-koa
• custom-server-polka

[leerob]

I think we can remove them in favor of the custom server example 👍