Adjustments to PIP position while flinging

Rather than using a scroller, find the actual edge intercept
based on the trajectory of the fling.

This is done by finding the two points it could intersect with
and checking which point is 'closer' (i.e. would be hit first
by the PIP).

Bias towards using the intersection with the top / bottom edge
if the PIP is being flung along the side it's currently on.

Also increases the maximum time for the fling.

Bug: 35358634
Test: manual - fling PIP around screen while in landscape
      and portrait
Change-Id: I26e943a5ddbc726ab86bc11e4271d4db034f3d47