This is more in line with wayland and it allows us to create new
interfaces in modules without having to add anything to the type
enum. It also removes some lookups to map type_id to readable
name in debug.
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.
Separate the session manager in a monitor and policy part.
The monitor manages the devices and endpoints.
The policy watches the nodes/ports/clients and applies the policy
of linking them.
Because both now have a separate connection, we can remove some
hacks in the protocol. When a remote was both the implementer and
user of an object we could get in a deadlock when the user was
blocked waiting and the implementator was blocked sending a reply.
We used to un-busy a client when it was expecting a reply from a
ping or sync for this reason.
Add and use some more keys for the endpoints and streams.
Remove override for resources, it can't work in general.
Rename method to add_object_listener to add a listener for
events/methods from the remote object.
Rename some methods to _call to call the interface and _notify
to notify the listeners.
Remove unused client event to be notified of resource
implementations.
