Add a new protocol helper implementation to consume Cephadm deployed NFS Ganesha.

This should make our driver code easier, delegating the NFS Ganesha administration to Cephadm instead to the manila operator as we currently do.

Communication with NFS Ganesha will be simplified as well, since we will use the interface provided by the nfs mgr plugin.

The current helper that relies on a manually deployed NFS Ganesha server and that communicates with it through DBUS will be maintained for compatibility.

Work to be completed:

• Add protocol helper with new implementation

Definition of Done:

• Code gets merged in upstream master branch
• Existing test suite (unit tests and integration tests) pass using the new configuration (cephadm deployed Ceph)