[Settings] Refactor hw keys handling with navbar presence (2/2)

This commit removes per hw keys disabler/enabler. Now all hw keys get their functionality observing navbar state. Navbar on = all hw keys disabled and navbar off = all hw keys enabledFinal clean-up in navbar handling. We now use key disabler hw support provided by CyanogenMod to totaly disable hw keys in devices supported by it. Since we have a navbar on/off option in all crDroid supported devices (because of Pie controls) and not all devices have key disabler support, crDroid also disable all hw keys in PhoneWindowManager.java if needed.

Change-Id: I1b173d491758838babd61aaba781991be67160ab