Use DecayAnimationSpec to animate to SwipeAnimation targetOffset

This CL makes SwipeAnimation.animateOffset() to use a DecaySpecAnimation
rather than a normal target animation after releasing a drag gesture
if the decay animation is enough to get to the target offset. This makes
the animation consume less velocity and makes the transition overscroll
behave more consistently w.r.t. overscrolling after a nested scrollable
is flung.

Bug: 378470603
Test: atest PlatformComposeSceneTransitionLayoutTests
Flag: com.android.systemui.scene_container
Change-Id: I38152f770942bf04cad57f3d98acd971ebe63d4d