As the KQS view is not extending the floating view, we have to
explicitly register the back action to close the KQS view.
Bug: 379778483
Test: open KQS via alt-tab/overflow button and tap the back button
Flag: com.android.launcher3.taskbar_overflow
Change-Id: I140813d1792f0c17aee5f9f8dd9fa3ed8b40ba6c