Add Ids to gtfs Features

[Alessandro100]

Gtfs features currently do not have a unique way to identify themselves. We need a way to uniquely identify features so that we can

• attach and use data with them reliably

We will need to add an id to the gtfs feature table

thoughts

• should we also add extra data to the features in the db? info url, category.. and in the frontend make an api call to get feature data?

[qcdyx]

Clarification: changes should be only on the UI, not the validator. spec team is responsible for manually managing the feature update in NOTICE_MIGRATION.md, then dev team apply changes on the UI.

Tasks:

• UI should do the mapping between old feature and new feature
• In the case of splitting features, we add new features
• individual documentation links to the features in the HTML report -> separate issue

[emmambd]

Need to review and approve #1812 before working on this so our features list is final

[emmambd]

Unblocked. Should use new features as written in https://github.com/MobilityData/gtfs-validator/blob/master/docs/FEATURES.md