healthd: move Android communication code to separate source

* add ops for different "modes" of healthd operation: android vs. recovery
* recovery mode selected by runstring options -r
* binder/Android communication moved to android mode
* recovery mode ops avoiding binder service registration
* "no service manager" flag removed; now handled by android vs. other modes

Change-Id: I3d8c89bf96a18a6a00cc85306f9a07d3f408f2a0