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/panelStackLayout.test.mjs

@@ -141,8 +141,8 @@ test('desktop panel lanes use per-panel allocations and presentation-only auto-c
   const ui = readShellSource();
   const css = readStylesheet(new URL('../style.css', import.meta.url));
   assert.doesNotMatch(ui, /_enforce(?:Left|Right)PanelAccordion/);
-  assert.match(rails, /classList\.add\('collapsed', 'layout-auto-collapsed'\)/);
-  assert.match(readFileSync(new URL('./ui/panelLayoutController.js', import.meta.url), 'utf8'), /classList\.remove\('collapsed', 'layout-auto-collapsed'\)/);
+  assert.match(rails, /onCollapse\(panel, \{ collapsed: true, auto: 'layout' \}\)/);
+  assert.match(readFileSync(new URL('./ui/panelLayoutController.js', import.meta.url), 'utf8'), /_presentPanel\(panel, \{ collapsed: false, auto: null \}\)/);
   assert.match(ui, /reconsiderAutoCollapse/);
   assert.match(
     ui,
@@ -169,7 +169,7 @@ test('desktop panel lanes use per-panel allocations and presentation-only auto-c
   assert.match(rightRail, /focusedExpandedPanel = expandedPanelsInDomOrder\.find\(\s*\(panel\) =>\s*panel\.contains\(documentRef\.activeElement\),?\s*\)/);
   // Collapse buttons render aria-expanded from the state the chrome presents
   // (panelChromeButtons.test.mjs covers the views).
-  assert.match(ui, /_chromeStore\.publish\(this\._chromeToken, panelEl\.id, \{\s*collapsed: panelEl\.classList\.contains\('collapsed'\),/);
+  assert.match(ui, /this\._presentPanel\(panelEl, \{ collapsed: nextCollapsed, auto: null \}\)/);
   assert.match(leftRail, /--left-panel-allocated-height/);
   assert.match(rightRail, /--right-panel-allocated-height/);
   assert.match(