Adds ai_recipe_generation sample (#2242)

Adding the demo app from my I/O talk. Because AI.

## Pre-launch Checklist

- [x] I read the [Flutter Style Guide] _recently_, and have followed its
advice.
- [x] I signed the [CLA].
- [x] I read the [Contributors Guide].
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] All existing and new tests are passing.

---------

Co-authored-by: Brett Morgan <brett.morgan@gmail.com>

ai_recipe_generation/lib/util/device_info.dart

@@ -0,0 +1,39 @@
+import 'package:device_info_plus/device_info_plus.dart';
+import 'package:flutter/foundation.dart';
+
+class DeviceInfo {
+  static Future<BaseDeviceInfo> initialize(DeviceInfoPlugin plugin) async {
+    if (kIsWeb) {
+      return await plugin.webBrowserInfo;
+    }
+    switch (defaultTargetPlatform) {
+      case TargetPlatform.android:
+        return await plugin.androidInfo;
+      case TargetPlatform.iOS:
+        return await plugin.iosInfo;
+      case TargetPlatform.macOS:
+        return plugin.macOsInfo;
+      case TargetPlatform.windows:
+        return await plugin.windowsInfo;
+      case TargetPlatform.linux:
+        return await plugin.linuxInfo;
+      default:
+        throw UnsupportedError(
+          'Device info not supported for this platform',
+        );
+    }
+  }
+
+  static bool isPhysicalDeviceWithCamera(BaseDeviceInfo deviceInfo) {
+    if (deviceInfo is! IosDeviceInfo && deviceInfo is! AndroidDeviceInfo) {
+      return false;
+    }
+    if (deviceInfo is IosDeviceInfo && deviceInfo.isPhysicalDevice) {
+      return true;
+    }
+    if (deviceInfo is AndroidDeviceInfo && deviceInfo.isPhysicalDevice) {
+      return true;
+    }
+    return false;
+  }
+}