New endpoint for schedules page - `scheduled_stop_times`

[matikin9]

Endpoint: /LACMTA/unique_shape_scheduled_stop_times/{route_code}?direction_id={direction_id}
Table name: unique_shape_stop_times

Hierarchy of data:
direction_id
list of day_of_week per direction
list of trips per day of week
list of stops per trip
list of departure times per stop

Discuss with Ani how we should structure the payload?

Add an endpoint where we pass in direction_id? We return the stop_lists (with departure_times for each stop) for all trips with unique shape_ids (for that route + direction_id).

[matikin9]

Future/End state - the idea for this is to allow us to have a dropdown where the user can select from all possible shapes, like how MBTA has their schedule pages.