Add predictive back animation for 3-button-nav

Bug: 373544911
Flag: com.android.window.flags.predictive_back_three_button_nav
Test: OverviewProxyServiceTest
Test: TaskbarNavButtonControllerTest
Test: TaskbarScrimViewControllerTest
Change-Id: I40cd4408c2d528e5ea17d76eaaa16021a0fcf94d
7 files changed