CallbackSaver
inline fun <T> CallbackSaver(delegate: Saver<T>, crossinline onSave: suspend (T?) -> Unit = {}, crossinline onRestore: suspend (T?) -> Unit = { }, crossinline onException: suspend (e: Exception) -> Unit = {}): Saver<T>
A Saver implementation that does nothing but invoke the given onSave, onRestore, onException callbacks when the state changes