doc: add http.IncomingMessage#connection

Refs: https://github.com/nodejs/node/issues/33715

* link message.socket
* deprecate
* update doc/api/http.md

PR-URL: https://github.com/nodejs/node/pull/33768


Reviewed-By: Robert Nagy <ronagy@icloud.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>