Feat: add a new control PathPicker, add PathPickerDemo

demo/Ursa.Demo/ViewModels/PathPickerDemoViewModel.cs

@@ -0,0 +1,10 @@
+using System.Collections.Generic;
+using CommunityToolkit.Mvvm.ComponentModel;
+
+namespace Ursa.Demo.ViewModels;
+
+public partial class PathPickerDemoViewModel : ViewModelBase
+{
+    [ObservableProperty] private string? _path;
+    [ObservableProperty] private IReadOnlyList<string>? _paths;
+}