Reenable auto generation of progress events on fling

This pulls the FlingAnimation from the AndroidX SpringAnimation library into core, which was left out in the CL with change-id Ifdf847da0aa2a6cf57e18f9ac7c91bb0fe3b12c2 when other parts of that library were added to core.

Bug: 333957271
Flag: com.android.systemui.predictive_back_system_anims
Test: atest BackProgressAnimatorTest
Test: atest FrameworksCoreTests:WindowOnBackInvokedDispatcherTest
Test: Manual, i.e. testing flings in app callbacks and analysing screen recordings
Change-Id: Idb64721703121414da847b11915a9c19e6bc2686