#5957560 Jetpack Thank you: include paragraph for users going through the logged-out checkout flow

Changes proposed in this Pull Request

Related to 1200152453830945-as-1200386304452705

• Users going through the new logged-out checkout flow should be explained that they need to go to their inbox in order to complete the account creation process.

Implementation notes

Instead of directly adding the new paragraph in the component, I decided to add the isUserlessCheckoutFlow prop to decide whether the message should be displayed. I did this because I anticipate that we are going to use the same Thank you page in the future for all Jetpack purchase flow, and not just this one. The rest of the flows don’t need this message since those flows don’t consider the creation of an account.

Testing instructions

• Download this PR and start Calypso Blue with yarn start.
• Visit http://calypso.localhost:3000/checkout/jetpack/thank-you/[site]/jetpack_complete replacing [site] with a site slug of a site you own.

Demo – before

Demo – after