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: I04cadc660f38e2d4541b06fcda950098a0768492
6 files changed