Microsoft.UI.Xaml v2.3.190909001-prerelease

https://www.nuget.org/packages/Microsoft.UI.Xaml/2.3.190909001-prerelease

Notable bug fixes:

• PTR: Fix high contrast list item display, update PTR test page (04fa7684 by chingucoding, pr #1273)
• Modify buttons inside TextBox, PasswordBox and AutoSuggestBox to correctly support rounded corners (fa64d7ed by rudyhuyn, pr #1269)
• Add reveal style to Settings button in NavigationView in top mode,Closes #942 (e5876718 by chingucoding, pr #1236)