Updated entrance animation for assistant handles.

Implemented piecewise overshoot-like interpolation in collaboration with
UX. Visually, the animation works the same, it's just broken up into
several chained animations for simpler tweaking.

Test: Visual evaluation
Bug: 134487710
Change-Id: Ifd1f16393014f7c30413adf91aea7407fb526992
1 file changed