Easter egg for touchpad gestures tutorial

Activated by doing three circles clockwise with two fingers on touchpad.

Fixes: 370496598
Test: EasterEggGestureTest
Test: Open any touchpad gesture tutorial and do three circles using two fingers
Flag: com.android.systemui.shared.new_touchpad_gestures_tutorial
Change-Id: I9bdf8f175e98c719f8c2de313aa26c8f549a560b