Now that we have reached a good level of consensus with the GTFS community on the list of existing GTFS Components, we want to complete their addition to this validator.

This spreadsheet contains the list of all GTFS Components, and the conditions under which we can them "present" in the validator.
The task is to add all components that have not been added yet.

Labelling this issue as "epic" because we might want to break it down into smaller increments.