Support wallet launch in Double Tap Power Gesture Settings

Modify Double Tap Power Gesture Settings screen to be able to set the
gesture to launch the wallet.

If the feature flag is disabled, the
Double Tap Power Gesture Settings screen defaults to the current
screen ("Quickly open camera"), which only provides the option to open the camera upon detecting the
gesture.

If the feature flag is enabled, the Double Tap Power Gesture Settings
screen defaults to the new "Double Tap Power Button" screen, which
provides the option to open the camera, the wallet, or neither upon
detecting the gesture.

Android Settings Feature Request: b/380287172

Bug: 378131008
Test: manual tested screen alternates based on feature flag
Test: atest DoubleTapPowerSettingsTest
Test: atest DoubleTapPowerPreferenceControllerTest
Test: atest DoubleTapPowerToOpenCameraPreferenceControllerTest
FLAG: android.service.quickaccesswallet.launch_wallet_option_on_power_double_tap

Change-Id: I1fc05ab3cfee2e86a80a1756655c368aae16747c