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
diff --git a/include/input/Input.h b/include/input/Input.h
index 2c4a511..805957a 100644
--- a/include/input/Input.h
+++ b/include/input/Input.h
@@ -241,6 +241,11 @@
     DEEP_PRESS = 2,
 };
 
+/**
+ * String representation of MotionClassification
+ */
+const char* motionClassificationToString(MotionClassification classification);
+
 /*
  * Pointer coordinate data.
  */