Extract editor classes out of test namespace and add anchor support

osu.Game/Skinning/Editor/SkinEditor.cs

@@ -0,0 +1,36 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
+using osu.Game.Graphics.Cursor;
+
+namespace osu.Game.Skinning.Editor
+{
+    public class SkinEditor : CompositeDrawable
+    {
+        private readonly Drawable target;
+
+        public SkinEditor(Drawable target)
+        {
+            this.target = target;
+
+            RelativeSizeAxes = Axes.Both;
+        }
+
+        protected override void LoadComplete()
+        {
+            base.LoadComplete();
+
+            InternalChild = new OsuContextMenuContainer
+            {
+                RelativeSizeAxes = Axes.Both,
+                Children = new[]
+                {
+                    target,
+                    new SkinBlueprintContainer(target),
+                }
+            };
+        }
+    }
+}