## Why
Some users prefer to use a custom server implementation that handles body parsing. If they do this, they have no way to opt out of all body parsing in API Routes. Requests with bodies die if next's `bodyParser` is not disabled. Requests just hang forever.
Instead of adding [this config](https://nextjs.org/docs/api-routes/api-middlewares#custom-config) to every API Route, we do a simple check to avoid parsing the body twice.
Fixes#8315Fixes#7960
