Implement seamless rotation mode.

Add a rotation mode which does not require freezing
the screen. For situations like Camera where only small
elements move on screen, this allows for seamless changes
of display orientation. This is achieved by transforming the
windows with their current buffer in the same transaction that
we rotate the display. We set things up so the windows are
frozen this way until they submit buffers in the new orientation.
There is a special case in the Camera window itself, and it's use
of NATIVE_WINDOW_TRANSFORM_INVERSE_DISPLAY. In this case the buffer
contents are rotated by SurfaceFlinger and will never resize, for these
windows we just need to update the scaling matrix.

Bug: 28823590
Change-Id: I52dc6a86fcb3c08f736f0977ba3975a24fb8136c