osdmonitor: allow users to set/clear cluster state flags (CEPH_OSDMAP_FULL)
While investigating a cluster that was failing to remove the OSDMap's full flag, we wished we had a command that would just do it. Normally if a user does this erroneously it will be re-set on the next OSDMonitor::tick() (default: 1 second intervals), but in this case the flag should have been cleared so if we could have manually done so, it would have avoided a few monitor restarts.
mon: allow full flag to be manually cleared
This is like a temporary measure as the mon will try to set them again,
but we have run into cases where the mon was misbehaving (failing to clear
the flag) and we wanted to do it. Note that the mon will likely set it
again on the next tick() anyway.
If we're going to clear it, we may as well be able to set it, too (again,
even if the mon is going to clear it soon). If nothing else this is useful
for writing tests.