Improve swipe to show notification menu gesture

- Increases minimum velocity for dismiss (100->500 dp/sec)
- Increases minimum distance for dismiss (40->60% of notification width)
- Alters logic when menu was already showing and notification
  gets moved (if it doesn't move enough sticks to menu, else it looks
  for dismiss or snap back into position)
- Changes swipe helper so that the dismiss direction takes the
  translation into account

Test: manual / had some people play with the gesture
Bug: 28693375
Change-Id: Ibe4c51627a78b9c3b7d889cf7e06a63da7113072