[#556] morph/neofs: Implement wrapper over contract client

Implement wrapper over NeoFS contact's client which allows you to
conveniently interact with the contract. Implement `ManageKeys` method
for binding or unbinding public keys to the NeoFS account.

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>

pkg/morph/client/neofs/wrapper/bind.go

@@ -0,0 +1,35 @@
+package neofscontract
+
+import (
+	neofscontract "github.com/nspcc-dev/neofs-node/pkg/morph/client/neofs"
+)
+
+// ManageKeys binds/unbinds list of public keys from NeoFS account by script hash.
+func (x *ClientWrapper) ManageKeys(scriptHash []byte, ks [][]byte, bind bool) error {
+	type args interface {
+		SetScriptHash([]byte)
+		SetKeys([][]byte)
+	}
+
+	var (
+		a    args
+		call func(args) error
+	)
+
+	if bind {
+		a = new(neofscontract.BindKeysArgs)
+		call = func(a args) error {
+			return (*neofscontract.Client)(x).BindKeys(*a.(*neofscontract.BindKeysArgs))
+		}
+	} else {
+		a = new(neofscontract.UnbindKeysArgs)
+		call = func(a args) error {
+			return (*neofscontract.Client)(x).UnbindKeys(*a.(*neofscontract.UnbindKeysArgs))
+		}
+	}
+
+	a.SetScriptHash(scriptHash)
+	a.SetKeys(ks)
+
+	return call(a)
+}

pkg/morph/client/neofs/wrapper/client.go

@@ -0,0 +1,27 @@
+package neofscontract
+
+import (
+	"fmt"
+
+	"github.com/nspcc-dev/neo-go/pkg/encoding/fixedn"
+	"github.com/nspcc-dev/neo-go/pkg/util"
+	"github.com/nspcc-dev/neofs-node/pkg/morph/client"
+	neofscontract "github.com/nspcc-dev/neofs-node/pkg/morph/client/neofs"
+)
+
+// ClientWrapper is a wrapper over NeoFS contract
+// client which provides convenient methods for
+// working with a contract.
+//
+// Working ClientWrapper must be created via NewFromMorph.
+type ClientWrapper neofscontract.Client
+
+// NewFromMorph wraps client to work with NeoFS contract.
+func NewFromMorph(cli *client.Client, contract util.Uint160, fee fixedn.Fixed8) (*ClientWrapper, error) {
+	sc, err := client.NewStatic(cli, contract, fee, client.TryNotary())
+	if err != nil {
+		return nil, fmt.Errorf("could not create client of NeoFS contract: %w", err)
+	}
+
+	return (*ClientWrapper)(neofscontract.New(sc)), nil
+}