Update the validator with spec modifications in Q3 2022

[isabelle-dr]

Describe the problem

The spec has advanced in Q3 2022 and the validator needs to be updated accordingly. The only PR that got merged in Q3 2022 on the GTFS Schedule Reference is:

• Add trip-to-trip transfers with in-seat option #303

Describe the changes

1. New validation rules for the following changes:

• from_stop_id and to_stop_id goes from Required to Conditionally required
• from_trip_id and to_trip_id goes from Optional to Conditionally required

2. Adding 4 and 5 as enum in transfers.transfer_type

Sample GTFS datasets

No response

Severity

ERROR

Additional context

No response

[isabelle-dr]

Closing, duplicate of #1264