Add a Feed form: ask producer to clarify when license is empty

[emmambd]

Describe the problem

If the official transit authority question is answered as "Yes" and no license is provided in the "Link to feed license" question, display a new required question that asks:

"Can you confirm that this feed is intended for trip planners and third parties to use?"

Proposed solution

See above

Alternatives you've considered

No response

Additional context

No response