Changes to Set up branded lookalike domains and mailboxes; start warmup.

added the new large_order_payment_pending enum value to the nextSteps/steps/items/reason response property for the response status 202

added the new optional request property dotComDomains

added the new optional request property prepaySecondMonth

added the optional property nextSteps/steps/items/effect/oneOf[#/components/schemas/MailboxBilling]/domainEnding to the response with the 202 status

added the optional property nextSteps/steps/items/effect/oneOf[#/components/schemas/MailboxBilling]/prepay to the response with the 202 status

added the optional property payment to the response with the 202 status