Add hmac to InputEvent and scale to MotionEvent

We need hmac for event verification and scale for supporting raw
coordinates properly.

Add these to InputEvent/MotionEvent/KeyEvent.

Bug: 134977432
Bug: 140786233
Test: atest libinput_tests inputflinger_tests
Change-Id: I688718dce98a38318a87e3a30d441b27bba93085