[webview_flutter] Implement clearLocalStorage/onHttpError and add integration tests based on upstream v4.13.1

[seungsoo47]

• Implement native Tizen support for clearLocalStorage and onHttpError, and bump webview_flutter_tizen to 0.10.1.
• Port the remaining runnable upstream v4.13.1 integration tests (onHttpError x2, clearLocalStorage) and align async style (await instead of unawaited()) with upstream.
• Stabilize the scroll position test by polling for the settled value instead of reading it once.
• Fix a WebView disposal race where engine-owned TBM surfaces could be freed while a raster-thread frame still read them, and work around a chromium-efl crash on the TV 10.0 emulator during teardown.
• flutter-tizen test (or example integration tests) on TV 10.0 emulator — 19/19 passing, including previously-crashing disposal cases

[gemini-code-assist]

Code Review

This pull request implements clearLocalStorage and onHttpError for the Tizen WebView, and addresses races, use-after-frees, and crashes during WebView disposal. Additionally, integration tests are updated to await controller calls instead of using unawaited. The reviewer feedback suggests awaiting the controller calls in the newly added onHttpError tests to maintain consistency with these changes.

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[gemini-code-assist]

To maintain consistency with the rest of the test suite and align with the PR's goal of using await instead of unawaited(), these controller calls should be awaited.

Suggested change

	unawaited(controller.setJavaScriptMode(JavaScriptMode.unrestricted));
	unawaited(
	controller.setNavigationDelegate(
	NavigationDelegate(
	onPageFinished: (_) => pageLoaded.complete(),
	onNavigationRequest: (NavigationRequest navigationRequest) async {
	NavigationDecision decision = NavigationDecision.prevent;
	decision = await Future<NavigationDecision>.delayed(
	const Duration(milliseconds: 10),
	() => NavigationDecision.navigate,
	);
	return decision;
	onHttpError: (HttpResponseError error) {
	errorCompleter.complete(error);
	},
	),
	),
	);
	unawaited(controller.loadRequest(Uri.parse('$prefixUrl/favicon.ico')));
	await controller.setJavaScriptMode(JavaScriptMode.unrestricted);
	await controller.setNavigationDelegate(
	NavigationDelegate(
	onHttpError: (HttpResponseError error) {
	errorCompleter.complete(error);
	},
	),
	);
	await controller.loadRequest(Uri.parse('$prefixUrl/favicon.ico'));

[gemini-code-assist]

To maintain consistency with the rest of the test suite and align with the PR's goal of using await instead of unawaited(), these controller calls should be awaited.

Suggested change

	unawaited(controller.setJavaScriptMode(JavaScriptMode.unrestricted));
	unawaited(
	controller.setNavigationDelegate(
	NavigationDelegate(
	onPageFinished: (_) => pageFinishCompleter.complete(),
	onHttpError: (HttpResponseError error) {
	errorCompleter.complete(error);
	},
	),
	),
	);
	unawaited(controller.loadHtmlString(testPage));
	await controller.setJavaScriptMode(JavaScriptMode.unrestricted);
	await controller.setNavigationDelegate(
	NavigationDelegate(
	onPageFinished: (_) => pageFinishCompleter.complete(),
	onHttpError: (HttpResponseError error) {
	errorCompleter.complete(error);
	},
	),
	);
	await controller.loadHtmlString(testPage);