Additional Assistant gesture tuning

=> Using the drag slop (currently 10dp), which is the appropriate slop when comparing to the other gestures. Touch slop (which was being used for the Assistant) is only being used for gestures starting from the back button. This means that the delegate was getting triggered much too often (unfair slop competition). This prevents that.

=> Fixed additional bugs with the consumer delegate / sharedState; the shared state notion really only applies to the OtherActivityInputConumer, and it wasn't being propagated from the AssistantConsumer.In addition, the isActive() method is only being used as a proxy for whether or not to use the shared state, so clarified the naming. This fixes another case where touch could become completely stuck and you could no longer swipe up.

=> Modified the effective angle to be 90 degrees down to 20 above the horizontal.

=> Reduced the drag threshold to 55 dps.

=> Known issue: the time threshold requires motion events to be triggered. In practice, this works because the finger doesn't stay completely still, but we should add a timer to update the progress smoothly.

=> Removed pause detector.

Change-Id: Ie23e836c6d778914594774b830c3cd2e7b94eca4