feat(panels): render each panel's state classes from the store

A panel's collapsed, dock-pinned, dock-pinned-top, layout-auto-collapsed
and accordion-collapsed classes are drawn by its root's v-panel-state from
the gev-panel-chrome store. PanelChrome, its restore, the layout
controller, both rails and the side accordion present each panel's state
there instead of writing its classes; the rails call onCollapse(panel,
{collapsed, auto}). The directive applies a change in a synchronous
watcher, since the rails measure a panel in the task that opens or closes
it.

Destroying the chrome inside Cockpit now puts back the panels Cockpit's
entry closed while it can still present them. Without a shell, the voice
tools' set_panel_open reports that there is no panel to open. QA scripts
present the states they set instead of writing the classes.

src/radioMarkup.test.mjs

@@ -359,7 +359,7 @@ test('panel collapse is presentation-only and Radio exposes explicit voice playb
   assert.doesNotMatch(enableMethod, /contextRadio/);
   assert.match(enableMethod, /toggleRadio\(this\._radioEnableBtn\)/);
   // The collapse buttons render aria-expanded from the state the chrome presents.
-  assert.match(ui, /_chromeStore\.publish\(this\._chromeToken, panelEl\.id, \{/);
+  assert.match(ui, /this\._presentPanel\(panelEl, \{ collapsed: nextCollapsed, auto: null \}\)/);
   assert.doesNotMatch(method, /panelId === 'global-context-panel'[\s\S]*?this\._radioState\?\.enabled[\s\S]*?setPanelCollapsed\('radio-panel', false\)/);
 });