Propagate MotionClassification to InputDispatcher

We added MotionClassification to MotionEvent and NotifyMotionArgs, but
the two have not yet been connected. Connect them here, to ensure that
apps can receive the classification.

Bug: 111480215
Test: atest -a libinput_tests inputflinger_tests
Change-Id: I67dda22d9ee8a2d89abf40dbd01200ec37a65737