[iOS] Add support for large titles in Shell

Introduces the UpdateLargeTitles method to manage large title display modes for navigation bars in ShellItemRenderer. This ensures that the large title preference is updated when the displayed page changes or when the view lays out subviews, aligning with iOS-specific platform configurations.

Author: kubaflo

src/Controls/src/Core/Compatibility/Handlers/Shell/iOS/ShellItemRenderer.cs

@@ -5,6 +5,7 @@
 using System.ComponentModel;
 using System.Linq;
 using Foundation;
+using Microsoft.Maui.Controls.PlatformConfiguration.iOSSpecific;
 using Microsoft.Maui.Graphics;
 using ObjCRuntime;
 using UIKit;
@@ -399,6 +400,7 @@ void OnDisplayedPageChanged(Page page)
 			{
 				_displayedPage.PropertyChanged += OnDisplayedPagePropertyChanged;
 				UpdateTabBarHidden();
+				UpdateLargeTitles();
 			}
 		}
 
@@ -408,6 +410,31 @@ void OnDisplayedPagePropertyChanged(object sender, PropertyChangedEventArgs e)
 				UpdateTabBarHidden();
 		}
 
+
+		void UpdateLargeTitles()
+		{
+			var page = _displayedPage;
+			if (page is null || !OperatingSystem.IsIOSVersionAtLeast(11))
+				return;
+
+			var largeTitleDisplayMode = page.OnThisPlatform().LargeTitleDisplay();
+
+			if (SelectedViewController is UINavigationController navigationController)
+			{
+				navigationController.NavigationBar.PrefersLargeTitles = largeTitleDisplayMode != LargeTitleDisplayMode.Never;
+				var top = navigationController.TopViewController;
+				if (top is not null)
+				{
+					top.NavigationItem.LargeTitleDisplayMode = largeTitleDisplayMode switch
+					{
+						LargeTitleDisplayMode.Always => UINavigationItemLargeTitleDisplayMode.Always,
+						LargeTitleDisplayMode.Automatic => UINavigationItemLargeTitleDisplayMode.Automatic,
+						_ => UINavigationItemLargeTitleDisplayMode.Never
+					};
+				}
+			}
+		}
+
 		void RemoveRenderer(IShellSectionRenderer renderer)
 		{
 			if (_sectionRenderers.Remove(renderer.ViewController))
@@ -441,6 +468,7 @@ IShellSectionRenderer RendererForViewController(UIViewController viewController)
 		public override void ViewWillLayoutSubviews()
 		{
 			UpdateTabBarHidden();
+			UpdateLargeTitles();
 			base.ViewWillLayoutSubviews();
 		}