make the icon converter delegate static to avoid unnecessary allocs

src/Avalonia.FreeDesktop/DBusTrayIconImpl.cs

@@ -41,7 +41,7 @@ namespace Avalonia.FreeDesktop
         public bool IsActive { get; private set; }
         public INativeMenuExporter? MenuExporter { get; }
         public Action? OnClicked { get; set; }
-        public Func<IWindowIconImpl, uint[]>? IconConverterDelegate { get; set; } 
+        public Func<IWindowIconImpl?, uint[]> IconConverterDelegate { get; set; } 
 
         public DBusTrayIconImpl()
         {

src/Avalonia.X11/X11Platform.cs

@@ -105,23 +105,25 @@ namespace Avalonia.X11
         public IntPtr DeferredDisplay { get; set; }
         public IntPtr Display { get; set; }
 
-        public ITrayIconImpl CreateTrayIcon ()
+        private static uint[] X11IconConverter(IWindowIconImpl? icon)
+        {
+            if (!(icon is X11IconData x11icon))
+                return Array.Empty<uint>();
+
+            return x11icon.Data.Select(x => x.ToUInt32()).ToArray();
+        }
+
+        public ITrayIconImpl CreateTrayIcon()
         {
             var dbusTrayIcon = new DBusTrayIconImpl();
 
             if (!dbusTrayIcon.IsActive) return new XEmbedTrayIconImpl();
-            
-            dbusTrayIcon.IconConverterDelegate = (icon) =>
-            {
-                if (!(icon is X11IconData x11icon))
-                    return Array.Empty<uint>();
 
-                return x11icon.Data.Select(x=>x.ToUInt32()).ToArray();
-            };
-            
+            dbusTrayIcon.IconConverterDelegate = X11IconConverter;
+
             return dbusTrayIcon;
         }
-
+        
         public IWindowImpl CreateWindow()
         {
             return new X11Window(this, null);