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.

ios/Runner/AppDelegate.swift

@@ -1,5 +1,8 @@
 import Flutter
 import UIKit
+import WebKit
+
+private let h5CacheChannelName = "io.openim.flutter.im_webview_app/h5_cache"
 
 @main
 @objc class AppDelegate: FlutterAppDelegate, FlutterImplicitEngineDelegate {
@@ -12,5 +15,31 @@ import UIKit
 
   func didInitializeImplicitFlutterEngine(_ engineBridge: FlutterImplicitEngineBridge) {
     GeneratedPluginRegistrant.register(with: engineBridge.pluginRegistry)
+    let h5CacheChannel = FlutterMethodChannel(
+      name: h5CacheChannelName,
+      binaryMessenger: engineBridge.applicationRegistrar.messenger()
+    )
+    h5CacheChannel.setMethodCallHandler { [weak self] call, result in
+      switch call.method {
+      case "clearAllWebsiteData":
+        guard let self else {
+          result(false)
+          return
+        }
+        self.clearAllH5WebsiteData(result: result)
+      default:
+        result(FlutterMethodNotImplemented)
+      }
+    }
+  }
+
+  private func clearAllH5WebsiteData(result: @escaping FlutterResult) {
+    let dataTypes = WKWebsiteDataStore.allWebsiteDataTypes()
+    WKWebsiteDataStore.default().removeData(
+      ofTypes: dataTypes,
+      modifiedSince: Date(timeIntervalSince1970: 0)
+    ) {
+      result(true)
+    }
   }
 }