Improve scoped service

Toolkit.Avalonia/FilePicker.cs

@@ -0,0 +1,31 @@
+using Avalonia.Controls;
+using Avalonia.Platform.Storage;
+using Toolkit.Foundation;
+
+namespace Toolkit.Avalonia;
+
+public class FilePicker(ITopLevelProvider topLevelProvider) :
+    IFilePicker
+{
+    public async Task<IReadOnlyCollection<string>> Get(FilePickerFilter filter)
+    {
+        if (topLevelProvider.Get() is TopLevel topLevel)
+        {
+            IReadOnlyList<IStorageFile> files = await topLevel.StorageProvider.OpenFilePickerAsync(new FilePickerOpenOptions()
+            {
+                AllowMultiple = filter.AllowMultiple,
+                FileTypeFilter =
+                [
+                    new(filter.Name)
+                    {
+                        Patterns = filter.Extensions is { Count: > 0 } ? filter.Extensions.Select(x => $"*.{x}").ToList() : ["*.*"]
+                    }
+                ]
+            });
+
+            return files.Select(x => x.Path.LocalPath).ToList();
+        }
+
+        return [];
+    }
+}