Revert "Only selectively compile Metal & fix some compilation issues"

This reverts commit beda3206e0.

src/Ryujinx/UI/Renderer/EmbeddedWindow.cs

@@ -1,5 +1,6 @@
 using Avalonia;
 using Avalonia.Controls;
+using Avalonia.Input;
 using Avalonia.Platform;
 using Ryujinx.Ava.Utilities.Configuration;
 using Ryujinx.Common.Configuration;
@@ -27,7 +28,7 @@ namespace Ryujinx.Ava.UI.Renderer
         protected nint WindowHandle { get; set; }
         protected nint X11Display { get; set; }
         protected nint NsView { get; set; }
-        public nint MetalLayer { get; protected set; }
+        protected nint MetalLayer { get; set; }
 
         public delegate void UpdateBoundsCallbackDelegate(Rect rect);
         private UpdateBoundsCallbackDelegate _updateBoundsCallback;