lnrpc+routerrpc+lncli: add amt and fee limit msat fields

rpcserver.go

@@ -3079,15 +3079,19 @@ func extractPaymentIntent(rpcPayReq *rpcPaymentRequest) (rpcPaymentIntent, error
 		// We override the amount to pay with the amount provided from
 		// the payment request.
 		if payReq.MilliSat == nil {
-			if rpcPayReq.Amt == 0 {
+			amt, err := lnrpc.UnmarshallAmt(
+				rpcPayReq.Amt, rpcPayReq.AmtMsat,
+			)
+			if err != nil {
+				return payIntent, err
+			}
+			if amt == 0 {
 				return payIntent, errors.New("amount must be " +
 					"specified when paying a zero amount " +
 					"invoice")
 			}
 
-			payIntent.msat = lnwire.NewMSatFromSatoshis(
-				btcutil.Amount(rpcPayReq.Amt),
-			)
+			payIntent.msat = amt
 		} else {
 			payIntent.msat = *payReq.MilliSat
 		}
@@ -3128,9 +3132,12 @@ func extractPaymentIntent(rpcPayReq *rpcPaymentRequest) (rpcPaymentIntent, error
 	// Otherwise, If the payment request field was not specified
 	// (and a custom route wasn't specified), construct the payment
 	// from the other fields.
-	payIntent.msat = lnwire.NewMSatFromSatoshis(
-		btcutil.Amount(rpcPayReq.Amt),
+	payIntent.msat, err = lnrpc.UnmarshallAmt(
+		rpcPayReq.Amt, rpcPayReq.AmtMsat,
 	)
+	if err != nil {
+		return payIntent, err
+	}
 
 	// Calculate the fee limit that should be used for this payment.
 	payIntent.feeLimit = lnrpc.CalculateFeeLimit(