test: check tls server verification with addCACert

SecureContext.addCACert() adds to the existing root store,
preserving root cert entries. option.ca is applied without
calling SecureContext.addRootCerts() so should add to
the default, empty, root store.

This test confirms that the built-in root CAs are not included
when options.ca is used.

Based on:

https://github.com/shigeki/node/commit/acd5837fd737351dd953b0387695705067cd69cb

PR-URL: https://github.com/nodejs/node/pull/10389


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>