[Base] Ability to turn HW keys on/off on supported devices (1/2)

- Enabled through overlay in devices repo

Change-Id: I5ca53bf60482392298c7ab6de3efe17abf20b2b9

Conflicts:
	core/java/android/provider/Settings.java
	core/java/android/view/ViewConfiguration.java
	core/res/res/values/cr_config.xml
	core/res/res/values/cr_symbols.xml
	policy/src/com/android/internal/policy/impl/PhoneWindowManager.java
Avoid SysUI force closing when enable/disable DSB System bar gradient option

Change-Id: I5d6dcea9f4d7187a9c14d8ef0dd5c1c874cb8d9f