fs: add fs.copyFile{Sync}

Fixes: https://github.com/nodejs/node/issues/14906
PR-URL: https://github.com/nodejs/node/pull/15034


Reviewed-By: Timothy Gu <timothygu99@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>