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.

This is now done by the config endpoint module

to make it more usable and compatible with g_idle_add

and drop the WpBaseEndpoint controls entirely

This keeps track of the default endpoint and selects a default
based on endpoint priorities when devices are discovered

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

Clear self->pending_endpoint before sending the done signal,
because the signal will trigger a new endpoint to be added in the
unit test and this may happen before g_clear_object is called,
in which case adding the new endpoint fails

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

This avoids hearing mono audio only on the left speaker