fix(instances): the VM list searches its VMs, collapses its hosts together and says when it is empty

- The search read a row's whole text, so a word on a button or in a
  state label matched every row. VM rows now carry data-search (the
  name, title and owners, and the host in the flat list), and
  table_filter.js searches that text when a row has it; the state has
  its own filter.
- Nothing matching left an empty table. table_filter.js shows the
  page's #no-match while no row does; the VM list's says so and offers
  "Clear the filters". A user with no VMs at all is told so instead of
  an empty table.
- The grouped list's "#" toggled each host on its own: a host
  collapsed by hand opened while the others closed. It now collapses
  every host, or opens them all once all are collapsed.
- One alert names every host the panel cannot reach, with why, in
  place of one dismissible alert per host; users who see no hosts keep
  their own message.
- A host's VM list showed a VM's maximum memory, the Instances page
  its current memory: both show the current memory now.
- The owners' users are prefetched with the VMs; the flat list's
  Bootstrap 4 font-italic is fst-italic.

computes/templates/computes/instances.html

@@ -72,7 +72,7 @@
                                 {% include 'instance_state.html' %}
                             </td>
                             <td data-sort="{{ instance.info.3 }}">{{ instance.info.3 }}</td>
-                            <td data-sort="{{ instance.info.1 }}"><p class="text-end">{% if instance.info %}{% widthratio instance.info.1 1024 1  %} MiB{% endif %}</p></td>
+                            <td data-sort="{{ instance.info.2 }}"><p class="text-end">{% if instance.info %}{% widthratio instance.info.2 1024 1  %} MiB{% endif %}</p></td>
                             <td class="text-nowrap">
                                 {% include 'instance_actions.html' %}
                             </td>