Create alternative .csv output of dataset listing for end users

[KarenJewell]

Is your feature request related to a problem? Please describe.
Currently, we offer our dataset listing in a .csv and .json download. The .csv was the original output of merge_data.py but is now being replaced by a .json file itself. This means we lose the .csv format for public users.

Describe the solution you'd like
Create and a .csv format of the dataset listing that users can download.

Describe alternatives you've considered
We've not considered where the .csv should live, so this is up for discussion.

Additional context
Original ticket triggering this change is #163