Creates a refund. (see note)

Use with caution. This action creates an Unlinked Refund that is not associated with an
Podium Invoice or Payment. This current implementation only works
with a Podium Payment Card Reader, reading the customer's credit card data
before debiting the refunded amount.

Balance requirements. This action requires that your account have on hand an amount
equal to or greater than the amount of the refund. The amount for this refund will be
deducted from the amount still to pay out from the account. If the account does not have
sufficient funds, the refund will fail.

Upcoming change: When this resource supports refunding a Podium Invoice,
/invoices/uid/refund is planned to be deprecated.

Required scope: write_payments.