Pods in scheduler cache contains both the scheduled pods and those not
scheduled yet in scheduling queue. This commit adds the second group of
pods into consideration while comparing the cache.
A debug tool that collects resources from api server and compares it
with the scheduler cache. It currently only compares the node list, but
it should be easy to extend. The compare is triggered by signal USER2,
by doing
kill -12 ${SCHED_PID}
The compare result goes to scheduler log.
Towards #60860
