The pw_remote object is really a wrapper around the pw_core_proxy.
The events it emits are also available in the core proxy and are
generally awkward to use.
With some clever new pw_core_proxy_* methods and a pw_core_connect
to create the core_proxy, we can convert all code away from pw_remote.
This is a first step in this conversion, using the pw_remote behind
the scenes. It leaks into some places because it really needs to become
its own struct in a next step.
Remove the parent_id from the global event. Remove the parent
and owner from the global object.
Use properties instead to mark parents and owners of objects.
Properties are easier to control for client exported objects and
usually a simple parent/child is not enough. For example, a client
exported node has the client as a parent but also the factory that
created the node.
