InputVerifier: fail on hover event with pointers down

Test: $ atest --host libinput_rust_test
Test: enable the verifier and play the recording from b/433623598, check
      it crashes
      $ adb shell 'stop && setprop log.tag.InputDispatcherVerifyEvents \
                   DEBUG && start'
      $ adb shell uinput - < recording2.evemu
Test: enable the verifier and use touchpad, mouse, and touchscreen for a
      while, check there aren't any crashes
Bug: 433623598
Flag: EXEMPT debugging and test code only
Change-Id: Ib30e227847d055937e4ecd171f8af319b5283bcf