inputdispatcher: Block touch while stylus is hovering

Before this CL, we only blocked touch when stylus was down. In this CL,
we change the behaviour to match the current behaviour inside
PreferStylusOverTouchBlocker: while stylus is hovering, reject touch.

That means:
1) While stylus is hovering, touch is ignored
2) If stylus starts hovering when touch is down, cancel touch

Bug: 308745008
Test: TEST=inputflinger_tests; m $TEST && $ANDROID_HOST_OUT/nativetest64/$TEST/$TEST
Change-Id: I3ebbc71753d67ef4603f8f018c529cb0474cd19e