Let users opt-in to email list
Downstream MR: https://gitlab.com/soapbox-pub/soapbox/-/merge_requests/33
During registration, this allows users to send an extra param,
accepts_email_list (bool) opting in to receive admin emails. This is separate from the Terms of Service box and is intended for sending a newsletter to users.
Two new endpoints are introduced:
These export CSVs meant to be imported into a third-party service like Mailchimp, Constant Contact, or anything else that can take a CSV.
subscribers.csv contains all local users who opted in while
unsubscribers.csv contains all other local users. It's important to have both in order to patch the external list.
Users may opt-in or opt-out with PATCH
accepts_email_list is false by default and not required.