Add predictive back animation to the compose bouncer

This is not required for flexiglass as the back animation is wired up through STL transitions for flexiglass.

Fixes: 375206941
Test: verified manually,
 1. Enable gesture nav
 2. Open bouncer
 3. Use gesture nav to go back to the lockscreen
 4. bouncer should shrink in size
Flag: com.android.systemui.compose_bouncer
Change-Id: I762186ec1503ef7a3975a7745f1f9fdc78a29811