PropertyGrid: simple handling of custom editors

In PropertyResolver, CreateEditor() uses the provided type or falls back to previous behavior

src/Shared/HandyControl_Shared/Controls/PropertyGrid/PropertyResolver.cs

@@ -102,7 +102,7 @@ namespace HandyControl.Controls
                     ? (PropertyEditorBase) new EnumPropertyEditor()
                     : new ReadOnlyTextPropertyEditor();
 
-        public virtual PropertyEditorBase CreateEditor(Type type) => new ReadOnlyTextPropertyEditor();
+        public virtual PropertyEditorBase CreateEditor(Type type) => Activator.CreateInstance(type) as PropertyEditorBase ?? new ReadOnlyTextPropertyEditor();
 
         private enum EditorTypeCode
         {