Add chargeled program for recovery

A small program to update the LED indicator based on charging status in
recovery. Build-blocked on RECOVERY_VARIANT=twrp so it doesn't interfere
with msm8960-common if that device-common exists.
* Green LED for charged
* Amber LED for charging
* LED off all other cases

Change-Id: I063013e312f5783f135732f63f8b4e1ba3695915