[TIMOB-10747] TiAPI: Ti.Gesture is for user input via hardware, not for the software response

On iOS, Ti.Gesture.Orientation maps to -[UIDevice orientation], which is the orientation of the hardware, not the navbar nor window. This serves as an input and suggestion taken along with Ti.UI.Window.orientationModes to rotate the UI, but itself is neither sufficient nor necessary to know the UI's orientation. When people conflate the device and UI's orientation (admittedly, they ARE the same on Android), confusion reigns.

Propose/recognize parity changes long overdue in terms of representing orientation (i.e., Ti.UI.orientation's deprecated in exchange for Ti.UI.Window.orientation)

Introduce an orientationChange event, either on Ti.Ui module or on the windows themselves.

Update documentation and examples to reflect this reality.