Add documentation for `arrivals-and-departures-for-location` endpoint

[3rabiii]

Description

The REST API documentation is currently missing a dedicated method page for the arrivals-and-departures-for-location endpoint.

Proposed Changes

To fix this, we need to:

1. Create a new method page (arrivals-and-departures-for-location.md) detailing all parameters.
2. Add a sample JSON response based on the legacy server's output.
3. Register the endpoint in rest_api.json so it appears in the navigation menu.
4. Update the arrivalAndDeparture element page to list this method as one of the endpoints that return it.