ofono: implement handling of SIM status notifications

Open-webOS-DCO-1.0-Signed-off-by: Simon Busch <morphis@gravedo.de>
ofono: create SIM manager instance when modem reports it's interface is supported

Open-webOS-DCO-1.0-Signed-off-by: Simon Busch <morphis@gravedo.de>
ofono: rework power status notifications to only be triggered on online property changes

Open-webOS-DCO-1.0-Signed-off-by: Simon Busch <morphis@gravedo.de>