Include themes XAML for WPF controls into SDK

**Why is this needed**: to better support very popular Copy Template feature in Visual Studio XAML designer.

**Details**: When .NET SDK is installed on target machine there are no *.xaml files which contain styles and templates for Button, CheckBox and other controls. Compare it with UWP SDK which installs generic.xaml. Currently VS install classic.xaml, aero.normalcolor.xaml, etc. for WPF Framework. However those files have not been updated since v4.5. WPF Core should address this by including such files into SDK. Consider following [Microsoft Guidelines](https://docs.microsoft.com/en-us/nuget/guides/create-ui-controls#add-design-time-support) for where and why to install such files.