Move QA scripts to the shared harness, batch 2 of 4

Each script launches and closes Chrome through scripts/qa/browser.mjs,
waits on the application through scripts/qa/ready.mjs instead of the
loading screen and fixed pauses, and reads the contract instead of
Cesium where the check is not about Cesium itself.

scripts/qa-layer-panel.mjs

@@ -1,13 +1,12 @@
 #!/usr/bin/env node
+import { whenSettled } from './qa/ready.mjs';
+import { launchBrowser, closeBrowser } from './qa/browser.mjs';
 /** Browser proof of Layers panel replacement and subscription ownership. */
-import puppeteer from 'puppeteer';
-const browser = await puppeteer.launch({
+const browser = await launchBrowser({
   headless: true,
   args: [
     '--no-sandbox',
-    ...(process.platform === 'darwin'
-      ? ['--use-angle=metal', '--enable-gpu']
-      : ['--use-gl=angle', '--use-angle=swiftshader']),
+    ...(process.platform === 'darwin' ? ['--enable-gpu'] : []),
   ],
 });
 const page = await browser.newPage();
@@ -26,6 +25,7 @@ try {
   await page.waitForFunction(() => window.__godsEyeView?.dataManager, {
     timeout: 60000,
   });
+  await whenSettled(page);
   const results = await page.evaluate(async () => {
     const manager = window.__godsEyeView.dataManager;
     const entry = document.querySelector(
@@ -139,7 +139,7 @@ try {
   for (const [name, passed] of results) check(name, passed);
   check('no uncaught browser errors', errors.length === 0);
 } finally {
-  await browser.close();
+  await closeBrowser(browser);
 }
 console.log(`RESULT: ${failures} failures`);
 process.exitCode = failures ? 1 : 0;