http2: allow passing FileHandle to respondWithFD

This seems to make sense if we want to promote the use
of `fs.promises`, although it’s not strictly necessary.

PR-URL: https://github.com/nodejs/node/pull/29876


Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Minwoo Jung <minwoo@nodesource.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>