client(ui): migrate to mvvm

ModpackUpdater.Apps.Client.Gui/App.axaml.cs

@@ -1,5 +1,6 @@
 using Avalonia;
 using Avalonia.Controls.ApplicationLifetimes;
+using Avalonia.Data.Core.Plugins;
 using Avalonia.Markup.Xaml;
 
 namespace ModpackUpdater.Apps.Client.Gui;
@@ -15,7 +16,26 @@ public partial class App : Application
     public override void OnFrameworkInitializationCompleted()
     {
         if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
-            desktop.MainWindow = new MainForm();
+        {
+            DisableAvaloniaDataAnnotationValidation();
+            desktop.MainWindow = new MainView
+            {
+                DataContext = new MainViewModel(),
+            };
+        }
         base.OnFrameworkInitializationCompleted();
     }
+
+    private void DisableAvaloniaDataAnnotationValidation()
+    {
+        // Get an array of plugins to remove
+        var dataValidationPluginsToRemove =
+            BindingPlugins.DataValidators.OfType<DataAnnotationsValidationPlugin>().ToArray();
+
+        // remove each entry found
+        foreach (var plugin in dataValidationPluginsToRemove)
+        {
+            BindingPlugins.DataValidators.Remove(plugin);
+        }
+    }
 }