cluster: add support for NODE_OPTIONS="--inspect"

When using cluster and --inspect as cli argument it is correctly
handled and each worker will use a different port, this was
fixed by #13619. But when env var NODE_OPTIONS="--inspect"
is set this logic doesn't apply and the workers will fail as they
try to attach to the same port.

Fixes: https://github.com/nodejs/node/issues/19026

PR-URL: https://github.com/nodejs/node/pull/19165


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>