Progress toward issue #2003.
Includes design from design doc PR #1578

Use init containers to create configuration for Ceph mgrs. There is only
one init container in this design. The init container calls the Rook
binary to create Ceph config files which are then shared with the mds
daemon main container.

Once this init is run, the main mds daemon is run. Leaving room to use
the Ceph-versioned image in the future, call `ceph-mds --foreground ...`
to run the Ceph mds.

The refactor to using an init container also necessitated refactoring
the mdses replicaset implementation to a deployment-per-pod
implementation due to a chicken-egg problem. With a single container (in
the before times) the Rook binary was able to call the ceph-mds daemon
with an id generated from the pod name. Since the pod name is not known
before runtime, and the id is one of the few params that must be
specified to Ceph daemons on run, it is necessary to know the id
beforehand; thus the move to a deployment architecture following the
likes of the mon and mgr daemons.
Signed-off-by: Blaine Gardner <blaine.gardner@suse.com>