Add tx hash for "Deposit" and "Withdraw" notifications

As the user can invoke several deposit or withdraw calls
inner ring nodes should be able to differ them even if they
have the same arguments. To do that neofs-contract notifies
about tx hash, which can be used as unique identifier of
withdraw or deposit operation.

neofs_contract.go

@@ -5,6 +5,7 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/interop/engine"
 	"github.com/nspcc-dev/neo-go/pkg/interop/runtime"
 	"github.com/nspcc-dev/neo-go/pkg/interop/storage"
+	"github.com/nspcc-dev/neo-go/pkg/interop/transaction"
 	"github.com/nspcc-dev/neo-go/pkg/interop/util"
 )
 
@@ -152,7 +153,10 @@ func Main(op string, args []interface{}) interface{} {
 			rcv = args[2].([]byte) // todo: check if rcv value is valid
 		}
 
-		runtime.Notify("Deposit", pk, amount, rcv)
+		tx := engine.GetScriptContainer()
+		txHash := transaction.GetHash(tx)
+
+		runtime.Notify("Deposit", pk, amount, rcv, txHash)
 
 		return true
 	case "Withdraw":
@@ -171,7 +175,10 @@ func Main(op string, args []interface{}) interface{} {
 			amount = amount * 100000000
 		}
 
-		runtime.Notify("Withdraw", user, amount)
+		tx := engine.GetScriptContainer()
+		txHash := transaction.GetHash(tx)
+
+		runtime.Notify("Withdraw", user, amount, txHash)
 
 		return true
 	case "Cheque":