Fix keyboard shortcuts to use Control on Windows and Linux (#3620)

* Fix keyboard shortcuts to use Control instead of Meta on Windows and Linux

* Convert more tests to use Playwright built-in

src/lib/utils.ts

@@ -1,6 +1,7 @@
 import { SourceRange } from '../lang/wasm'
 
 import { v4 } from 'uuid'
+import { isDesktop } from './isDesktop'
 
 export const uuidv4 = v4
 
@@ -126,6 +127,41 @@ export function getNormalisedCoordinates({
   }
 }
 
+// TODO: Remove the empty platform type.
+export type Platform = 'macos' | 'windows' | 'linux' | ''
+
+export function platform(): Platform {
+  if (isDesktop()) {
+    const platform = window.electron.platform ?? ''
+    // https://nodejs.org/api/process.html#processplatform
+    switch (platform) {
+      case 'darwin':
+        return 'macos'
+      case 'win32':
+        return 'windows'
+      // We don't currently care to distinguish between these.
+      case 'android':
+      case 'freebsd':
+      case 'linux':
+      case 'openbsd':
+      case 'sunos':
+        return 'linux'
+      default:
+        console.error('Unknown platform:', platform)
+        return ''
+    }
+  }
+  if (navigator.userAgent.indexOf('Mac') !== -1) {
+    return 'macos'
+  } else if (navigator.userAgent.indexOf('Win') !== -1) {
+    return 'windows'
+  } else if (navigator.userAgent.indexOf('Linux') !== -1) {
+    return 'linux'
+  }
+  console.error('Unknown platform userAgent:', navigator.userAgent)
+  return ''
+}
+
 export function isReducedMotion(): boolean {
   return (
     typeof window !== 'undefined' &&