Return natural orientation according to available screen size

It aligns the same policy as
TaskFragment#computeConfigResourceOverrides to resolve orientation.

Otherwise when the display size is close to square. A nosensor
activity may get natural orientation in portrait but get task
orientation in landscape, which causes unexpected letterbox.

e.g. physical screen size is 1000x1010 -> portrait
But screenWidthDp=500, screenHeightDp=490 (occupied by insets)
-> landscape

Bug: 233855302
Test: atest DisplayContentTests#testOrientationForAspectRatio
Change-Id: I6d148e6dc5fe543f20c0b5aef0fc9255c2e481aa