stream: fix finished writable/readable state

writable/readable does not indicate whether as stream is
a Writable/Readable. This implements a better check for
whether a object is a Writable/Readable.

PR-URL: https://github.com/nodejs/node/pull/31527


Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Minwoo Jung <nodecorelab@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>