rewrite into avalonia for linux support

NetworkDiagramAvalonia/App.axaml.cs

@@ -0,0 +1,28 @@
+using Avalonia.Controls.ApplicationLifetimes;
+using System.Net.Mime;
+using Avalonia.Markup.Xaml;
+using NetworkDiagramAvalonia.ViewModels;
+using NetworkDiagramAvalonia.Views;
+
+namespace NetworkDiagramAvalonia;
+
+public partial class App : MediaTypeNames.Application
+{
+    public override void Initialize()
+    {
+        AvaloniaXamlLoader.Load(this);
+    }
+
+    public override void OnFrameworkInitializationCompleted()
+    {
+        if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
+        {
+            desktop.MainWindow = new MainWindow
+            {
+                DataContext = new MainWindowViewModel(),
+            };
+        }
+
+        base.OnFrameworkInitializationCompleted();
+    }
+}