If an ordering of "rsc1 then rsc2" is configured, then probes of rsc2 should be ordered after starting rsc1.

Example use cases: rsc1 is a logical volume and rsc2 is a filesystem mounted on it; rsc1 is a filesystem and rsc2 uses an executable on that filesystem; rsc1 is dockerd and rsc2 is a Docker container.

This is very tricky to do without loops and corner cases. See order_then_probes() in pcmk_sched_probes.c.