Enable source generators in Sandbox.

samples/Sandbox/MainWindow.axaml.cs

@@ -6,17 +6,11 @@ using Avalonia.Win32.WinRT.Composition;
 
 namespace Sandbox
 {
-    public class MainWindow : Window
+    public partial class MainWindow : Window
     {
         public MainWindow()
         {
-            this.InitializeComponent();
-            this.AttachDevTools();
-        }
-
-        private void InitializeComponent()
-        {
-            AvaloniaXamlLoader.Load(this);
+            InitializeComponent();
         }
     }
 }

samples/Sandbox/Sandbox.csproj

@@ -4,6 +4,7 @@
     <OutputType>WinExe</OutputType>
     <TargetFramework>net6.0</TargetFramework>
     <TargetLatestRuntimePatch>true</TargetLatestRuntimePatch>
+    <IncludeAvaloniaGenerators>true</IncludeAvaloniaGenerators>
   </PropertyGroup>
 
   <ItemGroup>
@@ -17,4 +18,5 @@
   <Import Project="..\..\build\SampleApp.props" />
   <Import Project="..\..\build\ReferenceCoreLibraries.props" />
   <Import Project="..\..\build\BuildTargets.targets" />
+  <Import Project="..\..\build\SourceGenerators.props" />
 </Project>