Add display focus e2e platform test scenarios

Bug: 371094633
Flag: com.android.window.flags.enable_display_focus_in_shell_transitions
Test: atest OpenAndFocusTest
Test: atest ClickAndFocusTest
Test: atest DragAndKeepFocusTest
Test: atest MoveToNextDisplayAndFocusTest
Test: atest CloseThenMoveFocusTest
Change-Id: I2d67bb68697f6ad6a9c5c89320d28ae1578f0457
11 files changed