feat: Add build info and localization for entry app

- Introduced buildinfo.json5 to enable impeller feature.
- Added Chinese localization strings in string.json for module description and entry ability.
- Created Ability.test.ets for unit testing of ability functionalities.
- Implemented List.test.ets to run the ability tests.
- Developed TestAbility.ets to manage test execution and lifecycle events.
- Created Index.ets as a testability page with UI components.
- Added OpenHarmonyTestRunner.ts for managing test execution in OpenHarmony.
- Defined module.json5 for entry_test module configuration.
- Established color.json and string.json for base resources.
- Included icon.png for the test module.
- Created test_pages.json to define testability page sources.
- Configured hvigor and oh-package.json5 for project setup.
- Updated pubspec.yaml and related files to downgrade Dart SDK to 3.11.0 and adjust dependencies.
- Added PowerShell script to enable OpenHarmony Flutter toolchain.
- Updated multiple package pubspec.yaml files to align with Dart SDK version 3.11.0 and adjust dependencies accordingly.

packages/native_scan/example/pubspec.yaml

@@ -4,7 +4,7 @@ publish_to: none
 resolution: workspace
 
 environment:
-  sdk: ^3.12.0
+  sdk: ^3.11.0
 
 dependencies:
   flutter:

packages/native_scan/pubspec.yaml

@@ -10,7 +10,7 @@ resolution: workspace
 # 因此本包抛的是包内自定义的 NativeScanException，由调用方转成 NativeException。
 # ---------------------------------------------------------------------------
 environment:
-  sdk: ^3.12.0
+  sdk: ^3.11.0
 
 dependencies:
   flutter:
@@ -20,7 +20,9 @@ dev_dependencies:
   flutter_lints: ^6.0.0
   flutter_test:
     sdk: flutter
-  pigeon: ^27.3.0
+  # 27.x 需要 analyzer >=10，与 Harmony 兼容的 riverpod_generator 4.0.3
+  # （analyzer ^9）不能共存；26.3.1 同时兼容 Dart 3.11 与 analyzer 9。
+  pigeon: 26.3.1
 
 flutter:
   plugin: