events: expand NodeEventTarget functionality

Enable `NodeEventTarget` as a base class for `MessagePort`,
by enabling special processing of events for Node.js listeners,
and removing implicit constructors/private properties so that
classes can be made subclasses of `NodeEventTarget` after they
are created.

PR-URL: https://github.com/nodejs/node/pull/34057
Refs: https://twitter.com/addaleax/status/1276289101671608320


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: David Carlier <devnexen@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>