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/ui/visualSettings.js

@@ -445,8 +445,7 @@ export class VisualSettings {
       return;
     }
     if (!this._cockpitDisclosureOpen?.('display')) return;
-    this._sliderPanel.classList.remove('collapsed');
-    this._syncPanelCollapseButton(this._sliderPanel);
+    this._presentPanel(this._sliderPanel, { collapsed: false });
     this._lifetime.frame(() =>
       this._lifetime.frame(() => {
         this._sliderPanel?.scrollIntoView?.({ block: 'nearest' });
@@ -1434,8 +1433,7 @@ export class VisualSettings {
   _revealStyleParameters() {
     if (!this._sliderPanel?.classList.contains('active')) return;
     if (this._cockpitDisplayPortalActive) return;
-    this._sliderPanel.classList.remove('collapsed');
-    this._syncPanelCollapseButton(this._sliderPanel);
+    this._presentPanel(this._sliderPanel, { collapsed: false });
     this.setPanelCollapsed('pp-toggles', false, { explicit: true });
     this._lifetime.frame(() =>
       this._lifetime.frame(() => {