Send notification for registration information when submitted after the subscription is confirmed.

[lenopip]

For SaaS, when the buyer purchases a new contract, MP displays a "Confirm contract" success message and it provides a "Setup your account" button. If there is a delay on the buyer's side to complete the account setup, which involves navigating to the seller's registration page and completing entry of the form fields, then, the initial SNS notification from QuickStart does not contain any of the buyer information that is entered in the registration page. When the buyer completes the entry of the registration details subsequently, the information is getting stored in the DynamoDB table but there is no new SNS notification getting triggered to include the buyer contact details.

It would be a nice enhancement to QuickStart for a new notification to go out when the seller completes the registration page details.