Add fixed Route Identifier to trips endpoint, geography API and policy API

[Mu-yi-Zhou]

Is your feature request related to a problem? Please describe.

SFMTA figured a fixed route identifier of trip is necessary to manage our commuter shuttle program in San Francisco. Related to that, having trip_id in geography and policy API will be useful to specify geofencing zone and day/time resitriciton ect. for these regulated services.

Describe the solution you'd like

Add optional field route_id to Trips endpoint, geography API, and policy APi.

Is this a breaking change

• No, not breaking

Impacted Spec

For which spec is this feature being requested?

• agency
• policy
• provider
• geography

Describe alternatives you've considered

A clear and concise description of any alternative solutions or features you've considered.

Additional context

Add any other context or screenshots about the feature request here.