Update checkout data

[minkyngkm]

Done

• This PR was part of #13889. I separated one commit into this PR because #13889 is getting larger.
• The /account/checkout page seems to be used by both the pro shop and the credential shop, but it also needs to be used for the distributor store as well. Since the distributor store handles multiple products with different quantities, I updated the shopCheckoutData to support multiple products on the /account/checkout page.

QA

• Ensure purchases in the pro shop and credential shop work properly (Ensure the purchase processes in the pro shop and credential shop are not broken due to this PR)

[webteam-app]

Demo

Jenkins

demos.haus