build,tools: check freshness of doc addons

Add a `--check` flag to `tools/doc/addon-verify.js` and use that in the
`make test` target to determine if the generated files in `test/addons`
are fresh or stale.

PR-URL: https://github.com/nodejs/node/pull/17407


Reviewed-By: Richard Lau <riclau@uk.ibm.com>