Add CTS test for quick swipe back while the IME is shown

This test verifies that invoking a key back event twice quickly after each other will hide the IME first and then go back to the previous activity.

Bug: 375986921
Test: KeyboardVisibilityControlTest#testQuickDoubleSwipeBackHidesImeAndSendsEventToApp
Flag: android.view.inputmethod.refactor_insets_controller
Change-Id: I405fbcf99b59d0fd5873ee56de275679975805d0