What
We need to support some specific scenarios after checkout:

• after domain registration we should show thank you page with option to set the domain as primary
• after eCommerce purchase we should let the atomic transfer begin so the user can set up their store

This will fix the exceptions mentioned when closing #42545 bug report.

Why
Maintain the experience of users that are purchasing an eCommerce plan during launch or launching from wp-admin.

How (A/C)

• use the same approach as for the other products (implemented in Focused Launch: Only launch site if checkout is complete #48452) showing the checkout before launch but update the Success view with a link to the correct thank-you page.
• for wp-admin, since we are redirecting to /checkout page, we need to build some functionality into /checkout to handle the redirect when abandoning checkout (back to editor instead of /plans) as mentioned in Focused Launch: Only launch site if checkout is complete #48452 (comment)