Register tracking state listener (for onStartTracking/onStopTracking events)

/**
* Register tracking state listener
*
* @param listener Track state change listener
* @return true if listener registered
*/fun registerCallback(listener: TrackingStateListener): Boolean

/**
* Unregister tracking state listener
*
* @param listener
* @return true if listener unregistered
*/fun unregisterCallback(listener: TrackingStateListener): Boolean