[#973] ir: Listen and process Put/Delete events of Subnet contract

Define notification events, implement parsers. Add morph client of
Subnet contract. Listen, verify and approve events in Inner Ring app.

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

pkg/morph/event/subnet/put_test.go

@@ -0,0 +1,69 @@
+package subnetevents_test
+
+import (
+	"testing"
+
+	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
+	subnetevents "github.com/nspcc-dev/neofs-node/pkg/morph/event/subnet"
+	"github.com/stretchr/testify/require"
+)
+
+func TestParsePut(t *testing.T) {
+	var (
+		id    = []byte("id")
+		owner = []byte("owner")
+		info  = []byte("info")
+	)
+
+	t.Run("wrong number of items", func(t *testing.T) {
+		prms := []stackitem.Item{
+			stackitem.NewByteArray(nil),
+			stackitem.NewByteArray(nil),
+		}
+
+		_, err := subnetevents.ParsePut(createNotifyEventFromItems(prms))
+		require.Error(t, err)
+	})
+
+	t.Run("wrong id item", func(t *testing.T) {
+		_, err := subnetevents.ParsePut(createNotifyEventFromItems([]stackitem.Item{
+			stackitem.NewMap(),
+		}))
+
+		require.Error(t, err)
+	})
+
+	t.Run("wrong owner item", func(t *testing.T) {
+		_, err := subnetevents.ParsePut(createNotifyEventFromItems([]stackitem.Item{
+			stackitem.NewByteArray(id),
+			stackitem.NewMap(),
+		}))
+
+		require.Error(t, err)
+	})
+
+	t.Run("wrong info item", func(t *testing.T) {
+		_, err := subnetevents.ParsePut(createNotifyEventFromItems([]stackitem.Item{
+			stackitem.NewByteArray(id),
+			stackitem.NewByteArray(owner),
+			stackitem.NewMap(),
+		}))
+
+		require.Error(t, err)
+	})
+
+	t.Run("correct behavior", func(t *testing.T) {
+		ev, err := subnetevents.ParsePut(createNotifyEventFromItems([]stackitem.Item{
+			stackitem.NewByteArray(id),
+			stackitem.NewByteArray(owner),
+			stackitem.NewByteArray(info),
+		}))
+		require.NoError(t, err)
+
+		v := ev.(subnetevents.Put)
+
+		require.Equal(t, id, v.ID())
+		require.Equal(t, owner, v.Owner())
+		require.Equal(t, info, v.Info())
+	})
+}