Add hmac to InputEvent and scale to MotionEvent

We need to pass some additional data to the app to be able to construct
the MotionEvent.

For proper support of getRawX/getRawY, add the xScale and yScale to
MotionEvent.

For the verification of input events, add hmac to InputEvent.

Bug: 134977432
Bug: 140786233
Test: atest libinput_tests inputflinger_tests
Change-Id: Ia3400ebbd9698549aad4d97a3b789ab7e10f6b65