fs: use createDeferredPromise() in promises.watch()

This commit updates fsPromises.watch() to use the
createDeferredPromise() utility.

PR-URL: https://github.com/nodejs/node/pull/37386


Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>