allow mark any page as api router

[bluelovers]

Feature request

Is your feature request related to a problem? Please describe.

if we want api not inside /page/api folder or mixin page and api in same folder

we need use custom server
https://nextjs.org/docs/advanced-features/custom-server

i hope can more easy control it, without config next.config and custom server

Describe the solution you'd like

export enableApiRouter in any file
will mark this file is api router

page/my_api.ts

export const enableApiRouter = true;

export default (req, res) => {
  res.statusCode = 200
  res.setHeader('Content-Type', 'application/json')
  res.end(JSON.stringify({ name: 'John Doe' }))
}

Describe alternatives you've considered

A clear and concise description of any alternative solutions or features you've considered.

Additional context

Add any other context or screenshots about the feature request here.

[mmmeff]

+1 on this - my team needs to define its API routes behind a custom path to avoid conflicts with other pages. Having a way to configure this would be very helpful.

[ivanpetrushev]

+1 on this - we have independent 3rd party service that is requesting our api on another URL. Imagine 'https://our-domain.com/api-v1/stuff/method1/param1". We don't have access on how they are trying to access us, but we have to be compatible with them.

One possible solution will be to use rewrites. But docs say rewrites are only available in Node.js environment and we are targeting serverless buid.