http: support generic `Duplex` streams

Support generic `Duplex` streams through more duck typing
on the server and client sides.

Since HTTP is, as a protocol, independent of its underlying transport
layer, Node.js should not enforce any restrictions on what streams
its HTTP parser may use.

Ref: https://github.com/nodejs/node/issues/16256
PR-URL: https://github.com/nodejs/node/pull/16267


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>