refactor settleRailAndVerify: unpack into named SettlementResult to fix 'stack too deep'

Author: pali101

test/helpers/RailSettlementHelpers.sol

@@ -149,22 +149,8 @@ contract RailSettlementHelpers is Test {
         console.log("payeeFundsBefore", payeeAccountBefore.funds);
         console.log("payeeLockupBefore", payeeAccountBefore.lockupCurrent);
 
-        uint256 settlementAmount;
-        uint256 netPayeeAmount;
-        uint256 paymentFee;
-        uint256 operatorCommission;
-        uint64 settledUpto;
-        string memory note;
-
         vm.startPrank(payer);
-        (
-            settlementAmount,
-            netPayeeAmount,
-            paymentFee,
-            operatorCommission,
-            settledUpto,
-            note
-        ) = payments.settleRail(railId, untilEpoch);
+         (result.totalAmount, result.netPayeeAmount, result.paymentFee, result.operatorCommission, result.settledUpto, result.note) = payments.settleRail(railId, untilEpoch);
         vm.stopPrank();
 
         console.log("settlementAmount", result.totalAmount);
@@ -209,16 +195,6 @@ contract RailSettlementHelpers is Test {
 
         rail = payments.getRail(railId);
         assertEq(rail.settledUpTo, expectedUpto, "Rail settled upto incorrect");
-
-        return
-            SettlementResult(
-                settlementAmount,
-                netPayeeAmount,
-                paymentFee,
-                operatorCommission,
-                settledUpto,
-                note
-            );
     }
 
     function terminateAndSettleRail(