The driver inherits LinuxDriver for the OS surface and set TYPE_LABEL to
"Storage", but netOrk derives device_class from an issubclass chain that
reaches OSDriver before StorageDriver and returned "linux". The UI gates
the Storage tab on device_class === "storage", so an OMV device showed a
Storage label in the list and no Storage tab on the detail page — while
its disks, pools, volumes and shares were being collected and persisted
the whole time.
netOrk now honours an explicit DEVICE_CLASS attribute before falling back
to the chain, mirroring how it already honours TYPE_LABEL.
Refs christianmanivong/netork#111
