[#194] pkg/container: Implement container constructor with format check

Implement NewVerifiedFromV2 function that verifies format of NeoFS API V2
Container message.

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

pkg/container/fmt.go

@@ -0,0 +1,27 @@
+package container
+
+import (
+	"github.com/nspcc-dev/neofs-api-go/pkg"
+	"github.com/nspcc-dev/neofs-api-go/v2/container"
+	"github.com/pkg/errors"
+)
+
+// NewVerifiedFromV2 constructs Container from NeoFS API V2 Container message.
+// Returns error if message does not meet NeoFS API V2 specification.
+//
+// Additionally checks if message carries supported version.
+func NewVerifiedFromV2(cnrV2 *container.Container) (*Container, error) {
+	cnr := NewContainerFromV2(cnrV2)
+
+	// check version support
+	if err := pkg.IsSupportedVersion(cnr.Version()); err != nil {
+		return nil, err
+	}
+
+	// check nonce format
+	if _, err := cnr.NonceUUID(); err != nil {
+		return nil, errors.Wrap(err, "invalid nonce")
+	}
+
+	return cnr, nil
+}