Settings: Forward port Hardware key custom rebinding (2/2)

Settings for rebinding the actions performed on the following key press events:
Home long-press, menu press, menu long-press, search press, search long-press,
app-switch press and app-switch long-press.

The available actions are: Nothing, open/close menu, recent apps switcher,
search assistant, voice search and in-app search.

Devices with a key configuration other than home, back, menu and search need to
set config_deviceHardwareKeys in an overlay to have the correct preferences
show up.

Change-Id: Id04a598aeb9829d7971dedbd171a61999ce2f919