Use MobileDevice framework for iOS device notifications in plugin

Currently we use the USB/IOKit functionality to get notified that iOS devices are connected/disconnected from the computer, and use the USB serial number for identification. (iosdevice.cpp)

On the iostool side we use MobileDevice framework to actually access devices. (iosdevicemanager.cpp)

The issue is that the USB serial number now is no longer necessarily exactly equal to the iOS device ID that is used by the MobileDevice framework. It would be better to use the same mechanisms on both sides, so we do not have to make assumptions about the IDs.