http: return HTTP 431 on HPE_HEADER_OVERFLOW error

Instead of returning a generic 400 response when the
max header size is reached, return a 431 Request Header
Fields Too Large.

This is a semver-major because it changes the HTTP
status code for requests that trigger the header
overflow error.

PR-URL: https://github.com/nodejs/node/pull/25605
Fixes: https://github.com/nodejs/node/issues/25528
Refs: https://tools.ietf.org/html/rfc6585#section-5



Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>