src: add --napi-modules to whitelist

Add --napi-modules to whitelist for NODE_OPTIONS
as its needed so that we can run the tests that
come along with native modules.

PR-URL: https://github.com/nodejs/node/pull/12733


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>