Add new app close implementation.

- We remove the fling completely
- We set damping to 1 for x/y springs so there is no
  bounciness, and updated the stiffness and bounds to tighten
  up the path to the final location.
- During the animation, we translate all launcher content
  down
- When the x/y springs, and rect animator all finish,
  we use a spring to bounce the launcher content back up

- Added AppCloseConfig so that the entire animation can
  be defined in one location, with getter methods so that
  all the involved parties of the animation can access the
  current value.
- The animations are all defined linearly, and then
  interpolated over using a 3 point curve.

Building behind feature flag as we tune the values.

Bug: 173107751
Test: manual, visual
Change-Id: I83ad0fa2c4234cf30004240d43e191354595adc8