WinRT: Add missing manifest specifier for rotation

Add WINRT_MANIFEST.rotation_preference as description which orientation
is allowed or preferred by the app. Valid values for Windows Phone are
portrait, landscape, landscapeFlipped. WinRT also allows portraitFlipped

Task-number: QTBUG-40830
Change-Id: I6b11afcdb72c2c158dadddafc5d90c1d18ab9d8b
Reviewed-by: Andrew Knight <andrew.knight@theqtcompany.com>