initialize ibc transfer stack

Author: keithsue

app/app.go

@@ -777,6 +777,7 @@ func New(
 	// )
 
 	var transferStack ibcporttypes.IBCModule
+	transferStack = transfer.NewIBCModule(app.TransferKeeper)
 	transferStack = ibcfee.NewIBCMiddleware(transferStack, app.IBCFeeKeeper)
 	transferStack = ibccallbacks.NewIBCMiddleware(transferStack, app.IBCFeeKeeper, app.BtcBridgeKeeper, btcbridgetypes.DefaultMaxIBCCallbackGas)
 	// Since the callbacks middleware itself is an ics4wrapper, it needs to be passed to the transfer keeper