this commit add support for mirroring b/w implicit rados namespace and
defined rados namespace. To support this, rook will treat `<implicit>`
name on cephblockpool as `""` empty string. This will allow mirroring
b/w implicit and defined radosnamespace.
Signed-off-by: subhamkrai <srai@redhat.com>
(cherry picked from commit 420178fe3e)