win,build: build and test add-ons on test-ci

Added build-addons task, it allows to build and test native addons
during test-ci task. Basically it should work in same way like
Makefile "build-addons" task.

Reviewed-By: Rod Vagg <rod@vagg.org>
Reviewed-By: João Reis <reis@janeasystems.com>
PR-URL: https://github.com/nodejs/node/pull/5886
Fixes: https://github.com/nodejs/node/issues/2537