Migrate image entropy window from Eto.Forms to Avalonia.

Aaru.Gui/Views/ImageEntropyWindow.xaml.cs

@@ -0,0 +1,27 @@
+using System.ComponentModel;
+using Aaru.Gui.ViewModels;
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Markup.Xaml;
+
+namespace Aaru.Gui.Views
+{
+    public class ImageEntropyWindow : Window
+    {
+        public ImageEntropyWindow()
+        {
+            InitializeComponent();
+        #if DEBUG
+            this.AttachDevTools();
+        #endif
+        }
+
+        void InitializeComponent() => AvaloniaXamlLoader.Load(this);
+
+        protected override void OnClosing(CancelEventArgs e)
+        {
+            (DataContext as ImageChecksumViewModel)?.ExecuteStopCommand();
+            base.OnClosing(e);
+        }
+    }
+}