fs: add FileHandle object fd wrapper

The `node::fs::FileHandle` object wraps a file descriptor
and will close it on garbage collection along with a
process warning. The intent is to prevent (as much as
possible) file descriptors from being leaked if the user
does not close them explicitly.

PR-URL: https://github.com/nodejs/node/pull/18297


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>