feat: add selection list.

demo/Ursa.Demo/ViewModels/SelectionListDemoViewModel.cs

@@ -0,0 +1,17 @@
+using System.Collections.ObjectModel;
+using CommunityToolkit.Mvvm.ComponentModel;
+
+namespace Ursa.Demo.ViewModels;
+
+public class SelectionListDemoViewModel: ObservableObject
+{
+    public ObservableCollection<string> Items { get; set; }
+
+    public SelectionListDemoViewModel()
+    {
+        Items = new ObservableCollection<string>()
+        {
+            "Ding", "Otter", "Husky", "Mr. 17", "Cass"
+        };
+    }
+}