fix(node/fs): promises not exporting fs constants

[marvinhagemeister]

We were missing the constants export in the promise fs API which is available in node.

import { constants, promises } from "node:fs";
import { constants as fsPromiseConstants } from "node:fs/promises";
console.log(constants === promises.constants); // logs: true
console.log(constants === fsPromiseConstants); // logs: true

Fixes #21994