feat(instances): a VM's network devices as cards, each with its QoS limits

Settings > Network was a table whose fields were read-only inputs cut
off at phone width, an unlabelled "+", three icon buttons per NIC and
a separate QoS table keyed by MAC. The owner chose card layout from
three rendered options, with the QoS limits folding out like the
device details:

- A card per NIC: a VM's only NIC spans the row, two or more sit side
  by side from md. Each has its name and target, the link state as a
  switch, its source and IPv4 addresses, and "Device details"
  (type, MAC, model, NWFilter, IPv6) in a <details>.
- "QoS limits" in a second <details>, its summary naming the limited
  directions: a form per inbound or outbound limit, with Save and
  Delete limit, and the units.
- Labelled Edit, Add QoS and Delete in the card footer; "Add network
  device" by the heading. The edit and add-QoS dialogs are titled and
  labelled, and the edit dialog's fields have labels.

The limits come from each NIC of the persistent definition, so the QoS
table, Instance.config_qos and wvmInstance.get_all_qos are removed.

instances/models.py

@@ -168,11 +168,6 @@ class Instance(models.Model):
         edit does not post the live value back over it."""
         return self.proxy.get_disk_devices(config=True)
 
-    @cached_property
-    def config_qos(self):
-        """QoS of the persistent definition, which the QoS form changes."""
-        return self.proxy.get_all_qos(config=True)
-
     @cached_property
     def config_vcpu(self) -> int:
         """vCPUs of the persistent definition, which the CPU form changes."""