Add test for hover events over spy window

In this test, we check whether spy windows receive hover events.

Bug: 211379801
Test: m inputflinger_tests && adb sync data && adb shell -t /data/nativetest64/inputflinger_tests/inputflinger_tests
Change-Id: Ia4c0cbb889d1c9500b0b1696dc2f5690ef4550fe