Add a CheckboxPreference to enable/disable illumination bar

This option will be used to enable/disable illumination bar
upon hardware or softkey button press. Normally it'll not be
visible in settings unless users add ro.semc.illumination=true
in build.prop. This is done to avoid confusion on unsupported
device.
LEDs Bar CheckboxPreference translated to Spanish

CheckboxPreference strings added by @Agontuk in commit 0d87bbdf2b2c9f6c355629b950a69b4fbee9e6f7 translated to Spanish.
Add romanian illumination-bar fix translation
Add italian illumination-bar fix translation
Update strings.xml
Update strings.xml
Update strings.xml
Update strings.xml