Bills API improvements for vendor credits

In the bills API endpoints, we have introduced the capability of adding vendor credits to the bill. In the Create a bill (POST /v3/bills), Replace a bill (PUT /v3/bills/{billId}), and Update a bill (PATCH /v3/bills/{billId}) requests, you can now add vendor credits in the vendorCredits object.

Field	Description
`id`	BILL-generated ID of the vendor credit applied to the bill payment. The value begins with `vcr`.
`amount`	Credit amount

See Vendor credits for more information.