Merge PR #22717 into master

* refs/pull/22717/head:
	mgr/DaemonServer: osd purge: accept --yes-i-really-mean-it too
	mon,mgr: guard 'osd purge' with safe-to-destroy check
	mon/MonCommands: hide 'osd destroy-actual'
	mon/MonCommands: add HIDDEN flag
	mon,mgr: guard 'osd destroy' with 'osd safe-to-destroy' check
	mon/MonCommand: deprecate 'osd rm'
	mon/OSDMonitor: point users at 'ceph osd safe-to-destroy' for purge|destroy

Reviewed-by: Kefu Chai <kchai@redhat.com>
Reviewed-by: Josh Durgin <jdurgin@redhat.com>