MotionEvent: Add relative X and Y fields to PointerCoords

PointerCoord's axes AXIS_RELATIVE_X and AXIS_RELATIVE_Y are affected by
the MotionEvent's transform because they need to be rotated according to
the window orientation.

We add fields for those axes in PointerCoords, and ensure they are
rotated when populating the java instance from a native one.

Bug: 179274888
Test: build, manual with test app
Change-Id: Iab529ee7841d616678b48d301c059c9bf1311231