Microsoft.UI.Xaml v2.1.190606001

Minor updates to the 2.1 release based on bug reports that have come in since the release. Updates were cherry-picked from master:

Floatie:
CommandBarFlyout keyboarding updates and RTL keyboarding fix (#545)

TeachingTip:
TeachingTips display correctly when IsOpen is set early (#619)
Fix TeachingTip theming when page has RequestedTheme override (#637)
Set XamlRoot on TeachingTip so it can find its correct root in XamlIsland (#600)
Localization handback (#663)

Repeater:
Ensure that elements are refreshed when itemssource change when using non virtualizing layout (#639)
avoid reading index property on args during reset (#630)

NavigationView:
NavView Hamburger btn and header overlap on launch in minimal mode (#652)
Make consistency behaviour when clicking on a unselected item or clicking on a selected item (#589)

Misc:
Enable file version info in build (#745)