+ use the pw_proxy API to find the bound id instead
of relying on WpGlobal

This has the advantage that it works also for exported
objects and for objects that have been created by calling
into a remote factory (such as the link-factory), so we can
now know the global id of all proxies, not only the ones
that have been created by the registry.

This is not used anymore. It was useful when we were using it as
a detail in the global-added signal, but that is gone now.

They are equivalent, there is no real benefit in having both

The proxy takes more roundtrips to get updated and this makes the
policy fail to find a default endpoint at startup, right after
the devices have been discovered

This also removes the weak ref on the session, since the object
manager internally maintains a reference on the objects that
it manages.

to make it more usable and compatible with g_idle_add

This is useful to be able to call export() from a module init
function, which is called before the core is connected

These are set by the server on the global properties set

heavily based on the WpSession implementation

to avoid name clashing with the upcoming WpEndpoint interface
that is going to be the common interface of Wp{Proxy,Exported}Endpoint

Otherwise, if the object manager is destroyed while a sync is in progress,
we get an invalid 'self' pointer on the callback later, which is being
called regardless

There is a bit more work that should be done in the core to avoid leaking
this ref in case pipewire disconnects before the sync is completed