[Base] HW keys tweaks

PS: to enable this feature you need to set to true <bool name="config_hwKeysPref">true</bool> in device overlay. Of course this is for devices with hardware and capacitive keys ;)

Want to say thanks here for @Temasek, CyanogenMod Team and OmniRom Team

The hole inital idea of this commit is from Temasek with codes initially based on HW keys features from crDroid KK. 3-dots overflow button codes was ported from CM KK and some really useful ideas was taken from Omnirom sources.