src: implement getting current time in NodePlatform

It is required by a change in V8.
Refs: https://chromium-review.googlesource.com/c/v8/v8/+/598666

PR-URL: https://github.com/nodejs/node/pull/16271


Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Myles Borins <myles.borins@gmail.com>