Make struct spa_node_events for events emited from the main thread
and keep the spa_node_callbacks for the data thread callbacks.
The add_listener method installs the events and it's possible to
install multiple handles. Adding a listener first emits the info
and port_info events when installed, similar to how the PipeWire
proxy bind works.
This removes the need for the spa_pending_queue and makes it easier
to implement the _sync versions.
Add some helpers to make it easier for plugins to emit all the info
to new listeners.
Use the listeners for devices as well.
