ui(client): migrate to AvaloniaUI

ModpackUpdater.Apps.Client.Gui/Program.cs

@@ -1,4 +1,5 @@
-using Castle.Core.Logging;
+using Avalonia;
+using Castle.Core.Logging;
 using Newtonsoft.Json;
 using Pilz.Configuration;
 
@@ -23,9 +24,15 @@ public static class Program
     [STAThread]
     internal static void Main(string[] args)
     {
-        ApplicationConfiguration.Initialize();
-        AppGlobals.Initialize();
-        Application.Run(new MainForm());
+        BuildAvaloniaApp().StartWithClassicDesktopLifetime(args);
+    }
+
+    public static AppBuilder BuildAvaloniaApp()
+    {
+        return AppBuilder.Configure<App>()
+            .UsePlatformDetect()
+            .WithInterFont()
+            .LogToTrace();
     }
 
     private static string GetSettingsPath(int? settingsVersion = 3)