wasi: use missing validator

The `wasi` lib module's `initialize()` method is missing a validator.

PR-URL: https://github.com/nodejs/node/pull/39070


Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>