winrt: Enable window visibility for the root window.

winrt: Enable window visibility for the root window.

- Minimized and Hidden: hide the status bar and collapse winrt native ui element.
- Windowed and Maximized: show the status bar and re-size the window.
- FullScreen and AutomaticVisibility: hide the status bar and re-size the window.

Showing & hiding the status bar and re-sizing the window affect only the
windows phone build.

Change-Id: Iaa412382bffc14e470720f2213bb3f6851f57a6b
Task-Id: QTBUG-47811
Reviewed-by: Andrew Knight <andrew.knight@intopalo.com>