[webview_flutter_lwe] Update webivew_flutter to 4.4.2

[Swanseo0]

• Update webivew_flutter to 4.4.2.
• Update webview_flutter_platform_interface to 2.6.0.
• Update integration_test.
• Add pub topics to package metadata.
• Add support to retrieve the user agent. See LweWebViewController.getUserAgent.
• Apply Platform API change.
• Increase the minimum Flutter version to 3.3.

[JSUYA]

Can you check about onUrlChange added in webview_flutter v4.1.0?
The latest webview_flutter example code uses this API.

* Adds support to track URL changes. See `NavigationDelegate(onUrlChange)`.

[Swanseo0]

Can you check about onUrlChange added in webview_flutter v4.1.0? The latest webview_flutter example code uses this API.

* Adds support to track URL changes. See `NavigationDelegate(onUrlChange)`.

Upon updating webview_flutter to 4.4.2, it was checked whether the added functions (onUrlChange, onConsoleMessage) are supported by LWE, but it was confirmed that there is no related function.

[JSUYA]

Can you check about onUrlChange added in webview_flutter v4.1.0? The latest webview_flutter example code uses this API.

* Adds support to track URL changes. See `NavigationDelegate(onUrlChange)`.

Upon updating webview_flutter to 4.4.2, it was checked whether the added functions (onUrlChange, onConsoleMessage) are supported by LWE, but it was confirmed that there is no related function.

Yes, you can add UnimplementedError to LweNavigationDelegate for onUrlChange.

@override
  Future<void> setOnUrlChange(UrlChangeCallback onUrlChange) async {
    throw UnimplementedError(
        'This version of `LweWebViewController` currently has no '
        'implementation of `setOnUrlChange`.');
  }