Add feed_contact_email to schema

[Emma Blue]

What problem is your feature request trying to solve?
It's important for trip planners that they can contact the feed's producer to set up licensing agreements, address data quality issues, and other problems. Sometimes this data is provided in feed_info.txt and sometimes it's not. It would be helpful to include this info in the Mobility Database, as most contributors for the past 3 months have been sharing this information in their submission.

Describe the solution you'd like
A feed_contact_email field that is manually provided by the contributor.

Example: id=1924, feed_contact_email="[e-mail]"

[David Gamez]

Tasks:

• Add optional field to the DB catalog schema and the sources.csv(include one example)
• Add the field to the DB table
• Add the field to the feed response on the API
• Include the field in the DB populate script
• Include the field in the batch processing