Cleanup up overall usage of CephX statuses in CephCluster.
Convert all CephX statuses to non-pointer types. There is no specific
need for pointer types, and keeping these as non-pointers means there is
not a risk of nil pointer exceptions in all the various Rook controllers
for upgraded clusters.
Move initialization of CephCluster CephX status items to
`preMonStartupActions()`. This helps resolve 2 issues:
1. 'Uninitialized' state was being set for external CephClusters where
CephX statuses are not relevant.
2. 'Uninitialized' state was being set for upgraded clusters whose key
status cannot be determined.
Signed-off-by: Blaine Gardner <blaine.gardner@ibm.com>