When the resource does add_listener, send a message to the proxy
to trigger an emission of properties.
Block the client until all properties have been notified, track
this with a ping event to the implementation.
When the global is destroyed, free the resource.
When the resource is freed, destroy the global.
Make sure any bound resources are freed when the global is destroyed
by calling pw_global_add_resource().
Don't pass pw_properties around when we simply need to pass around
config info, only use pw_properties when used to construct an object
that keeps the properties.
The proxy API is the one that we would like to expose for applications
and the other API is used internally when implementing modules or
factories.
The current pw_core object is really a context for all objects so
name it that way. It also makes it possible to rename pw_core_proxy
to pw_proxy later.
Bind to the resource in create_object before we register the global.
This ensure a client gets to see the resource global id associated
with the resource before it appears in the registry, which makes it
easier to patch the local proxy to the global object.
Metadata allows apps to attach properties to objects that can be
read by other apps.
Not complete yet, properties should be removed when the object is
removed.
