Fix: problem fetching datasets with type 1 authentication.

[jcpitre]

Summary:

Datasets were not downloaded for mdb-2684.
mdb-2684 has type 1 authentication, meaning the token is passed as a query in the URL.
The base URL for this feed is: http://api.511.org/transit/datafeeds?operator_id=CE
The code would just append ?api_key=... to the base url, giving a resulting url with two ?
The correction is to use the & separator if the URL already has a ?.

Note this could fix other feeds with the same configuration.

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[Copilot]

Pull Request Overview

This PR fixes a bug in URL construction for datasets using type 1 authentication where the API key is passed as a query parameter. The issue occurred when the base URL already contained query parameters, causing malformed URLs with duplicate ? characters.

• Updates URL construction logic to properly handle existing query parameters
• Adds logic to detect existing query strings and use appropriate separator (& vs ?)
• Includes explanatory comments documenting the edge case