[iOS/Mac] Fixed the Border Rendering issues in CollectionViewHandler2 (#27801)

* Fixed the Border Rendering issues in CollectionViewHandler2

* Remove the unwanted namspace

* Removed UI test and added the device test

* Resolved the build errors

* Registered the cv2 handler inside the test to avoid other test failures

* Added a Assert.NotNull test

* Resolved the conflicts

Author: Ahamed-Ali

src/Controls/tests/DeviceTests/Elements/CollectionView/CollectionViewTests.iOS.cs

@@ -1,13 +1,17 @@
 using System;
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
+using System.Linq;
 using System.Threading.Tasks;
 using CoreGraphics;
 using Foundation;
 using Microsoft.Maui.Controls;
 using Microsoft.Maui.Controls.Handlers.Items;
+using Microsoft.Maui.Controls.Handlers.Items2;
+using Microsoft.Maui.Controls.Shapes;
 using Microsoft.Maui.Graphics;
 using Microsoft.Maui.Handlers;
+using Microsoft.Maui.Hosting;
 using Microsoft.Maui.Platform;
 using UIKit;
 using Xunit;
@@ -54,6 +58,61 @@ public CollectionViewStringGroup(string header, IEnumerable<string> data) : base
 			}
 		}
 
+		[Fact]
+		public async Task CollectionViewItemsArrangeCorrectly()
+		{
+			EnsureHandlerCreated(builder =>
+			{
+				builder.ConfigureMauiHandlers(handlers =>
+				{
+					handlers.AddHandler<CollectionView, CollectionViewHandler2>();
+					handlers.AddHandler<Border, BorderHandler>();
+					handlers.AddHandler<Label, LabelHandler>();
+				});
+			});
+
+			var items = Enumerable.Range(1, 50).Select(i => $"Item {i}").ToArray();
+
+			var collectionView = new CollectionView
+			{
+				ItemsSource = items,
+				MaximumHeightRequest = 300,
+				ItemTemplate = new DataTemplate(() =>
+				{
+					var label = new Label
+					{
+						HorizontalOptions = LayoutOptions.Center,
+						VerticalOptions = LayoutOptions.Center,
+					};
+					label.SetBinding(Label.TextProperty, ".");
+
+					return new Border
+					{
+						WidthRequest = 200,
+						StrokeShape = new RoundRectangle() { CornerRadius = 12 },
+						Content = label
+					};
+				}),
+				ItemsLayout = new GridItemsLayout(ItemsLayoutOrientation.Horizontal)
+				{
+					HorizontalItemSpacing = 50
+				}
+			};
+
+			await CreateHandlerAndAddToWindow<CollectionViewHandler2>(collectionView, handler =>
+			{
+				// Get the first cell's content
+				var firstCellContent = collectionView.GetVisualTreeDescendants().OfType<Border>().FirstOrDefault();
+
+				Assert.NotNull(firstCellContent);
+
+				var frame = firstCellContent.Frame;
+
+				Assert.True(frame.Width == 200 && frame.Height == 300);
+
+			});
+		}
+
 		[Fact]
 		public async Task CollectionViewContentRespectsMargin()
 		{