Shared storages were appearing multiple times (once per node) because
the deduplication logic only checked the Proxmox `Shared` flag. Many
storage types are inherently cluster-wide but don't set this flag:
- RBD (Ceph block storage)
- CephFS
- PBS (Proxmox Backup Server)
- GlusterFS
- NFS
- CIFS/SMB
- iSCSI
Now we detect shared storage based on both the Shared flag AND the
storage type. Inherently shared storage types are deduplicated and
shown once with a "cluster" node designation.
Related to #1049
rcourtman
96d06da0d7