Add aliases for Size and SizeF for UICatalog

Still needed in this csproj because of ambiguous naming from ImageSharp

UICatalog/UICatalog.csproj

@@ -42,5 +42,7 @@
     <Using Include="System.Drawing.RectangleF" Alias="RectangleF" />
     <Using Include="System.Drawing.Point" Alias="Point" />
     <Using Include="System.Drawing.PointF" Alias="PointF" />
+    <Using Include="System.Drawing.Size" Alias="Size" />
+    <Using Include="System.Drawing.SizeF" Alias="SizeF" />
   </ItemGroup>
 </Project>