Refactor H5 line management and cache handling in WebView app

- Introduced shared_preferences for initial H5 cache management.
- Added methods to clear H5 caches and probe line availability.
- Enhanced error handling for line loading and switching.
- Removed openim_common package and its configurations.
- Updated widget tests to reflect changes in H5 line handling and URL management.

pubspec.yaml

@@ -32,12 +32,11 @@ dependencies:
     sdk: flutter
 
   permission_handler: ^12.0.1
+  shared_preferences: ^2.5.5
   url_launcher: ^6.3.2
   webview_flutter: ^4.13.1
   webview_flutter_android: ^4.10.5
   webview_flutter_wkwebview: ^3.23.1
-  openim_common:
-    path: openim_common
 
 dev_dependencies:
   flutter_test: