test: add coverage for error apis

Add coverage for N-API functions related to
throwing and creating errors.  A number of these
are currently showing as not having any
coverage in the nightly code coverage reports.

PR-URL: https://github.com/nodejs/node/pull/12729


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>