Snake case used in enumerations on paymentItem

## What are the schemas that are affected by the issue
https://ns.adobe.com/xdm/data/paymentitem

In the enumeration for paymentType, snake-case is used for "credit_card", "debit_card", "gift-card", and others.

Is this desirable?

**Example below:**

"xdm:paymentType": {
"title": "Payment Type",
"type": "string",
"description": "The method of payment for this order. Enumerated, custom values allowed.",
"default": "other",
"meta:enum": {
"cash": "Cash",
"credit_card": "Credit Card",
"debit_card": "Debit Card",
"gift_card": "Gift Card",
"check": "Check",
"paypal": "PayPal",
"wire_transfer": "Wire Transfer",
"credit_card_reference": "Credit Card Reference Transaction",
"other": "Other"
}
},

Start with the paymentItem schema at the linked Adobe XDM URL and inspect the paymentType enumeration values shown in the issue. Determine whether the naming convention should change and identify all affected values; done requires a documented decision and consistent schema updates if the convention is changed.

Written by the indexing model from the issue text.