reserve-device: don't increment jack_n_acquired if it is 0 and use the updated value when setting data

if jack is running, that probably means that we want the jack
endpoints to be the default playback/capture path

This is necessary to finish augmenting nodes that advertise
PropInfo & Props in their param info but they don't actually have
any properties, so there is no param event emitted
(ex. the jack device nodes)

Because the sync is synchronous with the calls over the protocol,
the callback is ensured to be called after all the param events
have been emitted

otherwise we get stuck waiting for the param event
and we get warnings on the debug log

endpoint.description is now the user-friendly string
we want the endpoint name to be machine-friendly because it's
the identifier that we store in m-session-settings

this allows the created nodes to be able to set their "device.id"
property correctly

- fall back to the default logic if node.target is set but it doesn't exist
- use the default endpoint if it is within the [target-endpoint] matches;
  this way we can use a config file to override just the stream name,
  for instance, while still respecting the default endpoint
- prefer use of the lookup methods instead of manual iterations

previously the default endpoint was not respected because our config
files have a [target-endpoint] table..

they are not useful anymore because we hijack priv->info from the
impl subclass, so that it points to the impl info struct,
and therefore the base implementations work just fine

m-device-activation: use wp_core_timeout_add_closure instead of wp_core_timeout_add in reserve node API