New comments section in the requests/responses

frontend/pshared/lib/models/payment/intent.dart

@@ -17,6 +17,7 @@ class PaymentIntent {
   final FeeTreatment feeTreatment;
   final SettlementMode settlementMode;
   final Map<String, String>? attributes;
+  final String? comment;
   final Customer? customer;
 
   const PaymentIntent({
@@ -29,6 +30,7 @@ class PaymentIntent {
     this.fx,
     this.settlementMode = SettlementMode.unspecified,
     this.attributes,
+    this.comment,
     this.customer,
     required this.feeTreatment,
   });