src: give StreamBases the capability to ask for data

Add a `OnStreamWantsWrite()` event that allows streams to
ask for more input data if they want some.

PR-URL: https://github.com/nodejs/node/pull/18936


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>