qa/tasks/rook: deploy ceph via rook on top of kubernetes

qa/tasks/rook: deploy ceph via rook on top of kubernetes

This assumes that k8s is installed and kubectl works.

The ceph container to use is selected the same way the cephadm
task does it.

All scratch devices are consumed as OSDs.

A ceph.conf and client.admin keyring are deployed on all test
nodes, so normal tasks should work (if/when packages are installed).

Fixes: https://tracker.ceph.com/issues/47507
Signed-off-by: Sage Weil <sage@newdream.net>