Add ApplicationHighDpiMode property to project file.

## Summary
WinForms Designer is currently working on improving the HighDPI settings experience for .NET Core apps. For C#, they are reading the project file to get the property that a user manually edited. For VB, we currently save all Application Framework properties to the myapp file; however, the WinForms Designer doesn't have access to it. The request is to save that property both in the myapp file as well as the project file.

**myapp:**
`0`

**vbproj:**
`SystemAware`

The source of truth would still be the myapp file; this is mainly to unblock the WinForms Designer team.