Add WinFormsWithIslandApp, a simple WinForms app that hosts Xaml in an Island

[JesseCol]

Add WinFormsWithIslandApp, a simple WinForms app that hosts Xaml in an Island.

Please see the README.md file for more information.

Microsoft Internal Pipeline run: https://microsoft.visualstudio.com/ProjectReunion/_build/results?buildId=107164224&view=results