[#371] Support recent changes in NeoFS API protocol

Support:
  * new status codes (object, container, session);
  * object `Lock` message;
  * different signature schemes.

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

object/lock_test.go

@@ -0,0 +1,26 @@
+package object_test
+
+import (
+	"testing"
+
+	"github.com/nspcc-dev/neofs-api-go/v2/object"
+	objecttest "github.com/nspcc-dev/neofs-api-go/v2/object/test"
+	"github.com/stretchr/testify/require"
+)
+
+func TestLockRW(t *testing.T) {
+	var l object.Lock
+	var obj object.Object
+
+	require.Error(t, object.ReadLock(&l, obj))
+
+	l = *objecttest.GenerateLock(false)
+
+	object.WriteLock(&obj, l)
+
+	var l2 object.Lock
+
+	require.NoError(t, object.ReadLock(&l2, obj))
+
+	require.Equal(t, l, l2)
+}