refactor(instances): one way to reach a VM, its console and its devices

The .vv console file is built from the VM found by its UUID, with the
console page's getters, instead of looking the VM up by name five times;
a console without a listen address or password now gives 127.0.0.1 and
an empty password instead of "None". Removed methods nothing calls: the
by-name getters and power methods of wvmInstances, managed save, the vCPU
mode getter (it read the wrong attribute), the old NIC editor and its
bridge lookup. CD-ROM media and NIC hotplug use _definitions() like the
other device edits, the disk editor takes the bus prefix from
util.vol_dev_type, and an unreadable disk is logged, not printed.

instances/test_console_rule.py

@@ -52,17 +52,20 @@ class CanOpenConsoleTestCase(TestCase):
 
     def test_owner_can_download_vv_file(self):
         self.client.force_login(self.owner)
-        with patch("instances.views.wvmInstances") as mock_conn_cls, patch("instances.models.wvmInstance") as wvm:
-            wvm.return_value.instance.name.return_value = "cons-vm"
-            conn = mock_conn_cls.return_value
-            conn.graphics_type.return_value = "vnc"
-            conn.graphics_listen.return_value = "127.0.0.1"
-            conn.graphics_port.return_value = "5900"
-            conn.domain_name.return_value = "cons-vm"
-            conn.graphics_passwd.return_value = "secret"
+        with patch("instances.models.wvmInstance") as wvm:
+            proxy = wvm.return_value.cached_reads.return_value.__enter__.return_value
+            proxy.instance.name.return_value = "cons-vm"
+            proxy.host = "192.0.2.7"
+            proxy.get_console_type.return_value = "vnc"
+            proxy.get_console_listener_addr.return_value = "0.0.0.0"
+            proxy.get_console_port.return_value = "5900"
+            proxy.get_console_passwd.return_value = "secret"
             res = self.client.get(reverse("instances:getvvfile", args=[self.instance.id]))
         self.assertEqual(res.status_code, 200)
         self.assertIn(b"[virt-viewer]", res.content)
+        # the VM found by its UUID; a console on all addresses is reached through the host
+        for line in (b"type=vnc", b"host=192.0.2.7", b"port=5900", b"title=cons-vm", b"password=secret"):
+            self.assertIn(line + b"\n", res.content)
 
     def test_owner_can_get_vdi_url(self):
         self.client.force_login(self.owner)