policy-node: add support for passive links

When one of the nodes has node.passive, make a passive link.

Make virtual sinks and sources suspend properly when not in use.
6 jobs for passive-links in 6 minutes and 24 seconds (queued for 14 seconds)
Status Name Job ID Coverage
  Container
passed container_fedora #14584499

00:05:22

passed container_ubuntu #14584500

00:01:36

 
  Build
passed build_on_fedora_no_docs #14584502

00:00:36

passed build_on_fedora_with_docs #14584501

00:00:41

passed build_on_ubuntu_no_gir #14584504

00:01:00

passed build_on_ubuntu_with_gir #14584503

00:01:01