…route containing stop defined (#1663)

- Update `StopZoneIdValidator` to issue notice about a stop without `zone_id` defined only when the stop is contained in a trip contained in a route defined in a fare rule with zone fields defined.
- Change from previous logic which warned about stops without `zone_id` defined if any fare rules had zone fields defined.
- The warning is still only triggered for stops of location type `0`.
- Zone fields in `fare_rules.txt` are `origin_id`, `destination_id`, and `contains_id`.

Merge remote-tracking branch 'refs/remotes/origin/master'