Check timeserver per train

@schmidtp as I mentioned on Zulip, maybe the check for timeserver-ordained train ID should go in input handler. Is this a reasonable approach? In case there is never a timeserver, all trains are probably discarded. Unless dataFormat.trainFromFutureThreshold is set really high (the during-init warning currently seen at SPB at least also sets the threshold super high so it's just a warning and not discarding), of course.

Could also do separate BOOL of whether or not to threshold and just decide to not threshold in case we don't know the time (instead of guessing based on last processed train).