Resolve ambiguous reference issues

Author: Edward Miller

src/Core/src/Platform/Windows/ContentPanel.cs

@@ -1,10 +1,12 @@
-#nullable enable
+#nullable enable
 using System;
 using System.Numerics;
 using Microsoft.Graphics.Canvas;
 using Microsoft.Maui.Graphics;
 using Microsoft.Maui.Graphics.Platform;
+#if MAUI_GRAPHICS_WIN2D
 using Microsoft.Maui.Graphics.Win2D;
+#endif
 using Microsoft.UI.Composition;
 using Microsoft.UI.Xaml;
 using Microsoft.UI.Xaml.Hosting;

src/Core/src/Platform/Windows/WrapperView.cs

@@ -4,7 +4,9 @@
 using Microsoft.Graphics.Canvas;
 using Microsoft.Maui.Graphics;
 using Microsoft.Maui.Graphics.Platform;
+#if MAUI_GRAPHICS_WIN2D
 using Microsoft.Maui.Graphics.Win2D;
+#endif
 using Microsoft.UI.Composition;
 using Microsoft.UI.Xaml;
 using Microsoft.UI.Xaml.Controls;