rbd: delegate map requests to the Windows service

rbd: delegate map requests to the Windows service

At the moment, rbd-wnbd daemons are tied to the Windows
session. When the user logs off or the WinRM remote session
terminates, the daemons are killed.

In order to avoid such issues, we'll delegate the daemon
initialization to the centralized Ceph Windows service.

We're using a named pipe for the Ceph service communication.
We're not using Ceph admin sockets for now since unix sockets
aren't available on Windows Server 2016.

Worth mentioning that the Ceph Windows service will restart
registered mappings when the host reboots based on the command
lines saved in the Windows registries. Writing to the registry
key as well as the service named pipe requires admin privileges.

Signed-off-by: Lucian Petrut <lpetrut@cloudbasesolutions.com>