Tune launch animations.

This CL tunes the launch animations so that we:
 * scale the opening window with the expanding view.
 * center the window in the x-axis (while keeping it top-aligned in the
   y-axis).

Bug: 186189658
Test: Click notification, QS tile, media, etc
Change-Id: Icbbc4cb07d2d9390b757163640b0cbb8302e2a94