feat: [XBAP-17277] expose BrandingThemeID on Prepayment schema and response examples

Author: Ripal Parikh

xero_accounting.yaml

@@ -12632,6 +12632,7 @@ paths:
                     ID: ce0cddef-cf5a-4e59-b638-f225679115a7
                     CurrencyRate: 1.000000
                     Type: RECEIVE-PREPAYMENT
+                    BrandingThemeID: 414d4a87-46d6-4cfc-ab42-4e29d22e5076
                     Reference: INV-0011
                     RemainingCredit: 3449.00
                     Allocations:
@@ -23921,6 +23922,10 @@ components:
           description: Xero generated unique identifier
           type: string
           format: uuid
+        BrandingThemeID:
+          description: The unique identifier of the branding template applied to a receive prepayment
+          type: string
+          format: uuid
         CurrencyRate:
           description: The currency rate for a multicurrency prepayment. If no rate is specified, the XE.com day rate is used
           type: number