Update Validator after addition of trip-to-trip and route-to-route transfers

[isabelle-dr]

In Q4 2021, trip-to-trip and route-to-route transfers were added to the specification (PR#284).

The validator needs to be updated with 4 additional optional fields in transfers.txt:

• from_trip_id - Foreign key referencing trips.trip_id
• to_trip_id - Foreign key referencing trips.trip_id
• from_route_id - Foreign key referencing routes.route_id
• to_route_id - Foreign key referencing routes.route_id

No additional rules need to be added.

Definition of done:

• the ForeignKeyViolationNotice is triggered if these fields are referencing a value that doesn't exist.
• the UnknownColumnNotice is not triggered by these four fields.

[KClough]

@isabelle-dr please let me know if I should be updating the status of things on this board. I didn't see a way for me to set that status from Current Sprint to Under Review.

[maximearmstrong]

@isabelle-dr please let me know if I should be updating the status of things on this board. I didn't see a way for me to set that status from Current Sprint to Under Review.

I just updated it :) Thank you @KClough ! Can you update it via the projects section (right bar) of this issue?