feat: add button group.

src/Ursa/Controls/ButtonGroup.cs

@@ -0,0 +1,23 @@
+using System.Net.Http.Headers;
+using Avalonia;
+using Avalonia.Collections;
+using Avalonia.Controls;
+using Avalonia.Controls.Primitives;
+using Avalonia.Media;
+using Avalonia.Metadata;
+
+namespace Ursa.Controls;
+
+public class ButtonGroup: ItemsControl
+{
+    protected override bool NeedsContainerOverride(object? item, int index, out object? recycleKey)
+    {
+        recycleKey = null;
+        return item is not Button;
+    }
+
+    protected override Control CreateContainerForItemOverride(object? item, int index, object? recycleKey)
+    {
+        return new Button();
+    }
+}