Adding velocity threshold for home touchpad gesture

Also creating fake for VelocityTracker and reusing it in recent apps gesture test

Test: HomeGestureRecognizerTest
Test: manual, home gesture is not successful if gesture is done slowly
Fixes: 365787507
Flag: com.android.systemui.shared.new_touchpad_gestures_tutorial
Change-Id: Ibcc92a3562278bff7522f4c096bacbe72a30331f