Improve maximizing dock/clip reveal animation

There was a very visible hole at the end of the transition when both
the docked stack expands and the other app is doing a clip reveal
animation, but only if the app had to travel a far distance to
meet it's target rectangle.

To fix this, we interpolate between two animation curves for maximizing
divider: One is the original curve, and the other one is an adjusted
one which simulate if the divider would start at the edge of the app
surface that plays the clip reveal animation. At the start of the
animation, we use the original curve, but then about in the middle of
the animation we interpolated towards the adjusted curve, so the divider
meets the edge of the app surface that plays the clip reveal animation,
eliminating that gap while still preserving the overall motion.

Bug: 27154882
Change-Id: I37716588f88ddc643ed6176c2ccd56ca174e8919