Refactoring recent app gesture recognition logic

Part of introducing gesture live progress tracking.
Adding VelocityTracker so we can not only track distance but also velocity.
Making RecentAppsGestureMonitor overall simpler and nicer.

Bug: 369817369
Test: All tests are passing
Flag: com.android.systemui.shared.new_touchpad_gestures_tutorial
Change-Id: Ib0b8d038acea3417c83ef4cc3a8043ff74bf9504