Added ContextMenu/Flyout animations. Added platform services. Use bitmap cache for all views.

Harmonia.UI/Platform/ClipboardLocator.cs

@@ -0,0 +1,17 @@
+using Avalonia.Controls;
+using Avalonia.Input.Platform;
+
+namespace Harmonia.UI.Platform;
+
+public class ClipboardLocator : PlatformServiceLocator<IClipboard>, IClipboardLocator
+{
+    protected override IClipboard? GetFromWindow(Window mainWindow)
+    {
+        return mainWindow.Clipboard;
+    }
+
+    protected override IClipboard? GetFromTopLevel(TopLevel topLevel)
+    {
+        return topLevel.Clipboard;
+    }
+}