fs: make URL paths no longer experimental

PR-URL: https://github.com/nodejs/node/pull/18591


Reviewed-By: Weijia Wang <starkwang@126.com>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Tiancheng "Timothy" Gu <timothygu99@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>