[TODO] Configure confirmation emails to be sent following a successful user registration

[connoro7]

To do:

• Configure mail protocols for sending confirmation emails
• Configure user data model to accept "Confirmed email address" boolean value
• Configure routing for (time-sensitive) URLs that will fire off EMAIL_CONFIRM_SUCCESS action when client navigates to the URL
• Ensure routes are protected: confirmation only occurs if the client possesses the correct Bearer token
• If user places an order with an unconfirmed email address, send notification to admin user(s) so that order details can be reviewed/processed manually (to reduce incidence of fraudulent orders)