env: introduce `KickNextTick`

There might be a need to "kick off" the next tick queue and execute
events on it. Normally it is done through the `MakeCallback` interface,
but in case when it is not - we need a way to "kick them off" manually.

PR-URL: https://github.com/nodejs/node/pull/2355


Reviewed-By: Trevor Norris <trev.norris@gmail.com>