feat(instances): a VM's access in one strip, its console password kept to its rule

The Access tab hid the console, the root password, the SSH key and the
remote viewer behind four sub-tabs. The owner chose a compact layout
from three rendered options: the state, a strip with the console and
the remote viewer, then two rows for root's password and key, each
saying why it waits when it does.

Codex reviewed access end to end; these are fixed:

- console.vv carries the console password only for users with the
  passwordless console permission, as the console page passes it; it
  gave it to every user who may open the console.
- The root password field is a labelled password input, not plain text
  with a 24-character limit.
- Without a saved public key the key row is disabled and points to the
  profile, instead of offering "None".
- A paused VM's console opens, as the console view allows.
- The remote viewer address and console.vv show only for a VNC or SPICE
  console that listens beyond the host's loopback; a viewer on the
  user's computer cannot reach the others, and a serial console gave a
  pty://…:None address.

instances/templates/instance.html

@@ -198,7 +198,7 @@
             $("#video_model_select option[value='" + video_model + "']").prop('selected', true);
         }
     });
-{% if can_open_console %}
+{% if can_open_console and vdi_reachable %}
     $(document).ready(function () {
         // set vdi url
         $.get("{% url 'vdi_url' compute.id instance.name %}", function(data) {