build: build addon tests in parallel

Use a JS script to build addons rather than a shell command
embedded in the Makefile, because parallelizing is hard in sh
and easy in JS.

PR-URL: https://github.com/nodejs/node/pull/21155


Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>