fix(TextBox): [iOS] Add temporary workaround for iOS 16 on selection …

…with UITextField

This change is needed to make the SinglelineTextBoxView.SelectedTextRange conditional, and avoid changing the value provided to UIKit. This breaks the use of `TextBoxSelectionChanged`, but can be restored by using the `FeatureConfiguration.TextBox.IOS16EnableSelectionSupport` feature flag if the issue ends up being fixed in UIKit. See #9430 for more details.

src/Uno.UI/FeatureConfiguration.cs

@@ -434,6 +434,7 @@ public static class TextBlock
 
 		public static class TextBox
 		{
+
 			/// <summary>
 			/// Determines if the caret is visible or not.
 			/// </summary>
@@ -451,6 +452,15 @@ public static class TextBox
 			/// </remarks>
 			public static bool UseLegacyInputScope { get; set; }
 #endif
+
+#if __IOS__
+			/// <summary>
+			/// As of iOS 16 Beta 4, the selection events are crashing the application. This feature configuration is added
+			/// to provide the ability to restore the original behavior if/when the underlying UIKit is fixed.
+			/// See https://github.com/unoplatform/uno/issues/9430 for additional details.
+			/// </summary>
+			public static bool IOS16EnableSelectionSupport { get; set; }
+#endif
 		}
 
 		public static class ScrollViewer