[#83] client: Implement status library

Define base `Status` interface. Provide the functionality to distinguish
success and failure returns. Provide functionality to transport statuses
over NeoFS API V2 protocol. Support success `OK` and failure `INTERNAL`
returns.

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

client/status/unrecognized.go

@@ -0,0 +1,18 @@
+package apistatus
+
+import (
+	"github.com/nspcc-dev/neofs-api-go/v2/status"
+)
+
+type unrecognizedStatusV2 struct {
+	v2 status.Status
+}
+
+func (x unrecognizedStatusV2) Error() string {
+	return errMessageStatusV2("unrecognized", x.v2.Message())
+}
+
+// implements method of the FromStatusV2 local interface.
+func (x *unrecognizedStatusV2) fromStatusV2(st *status.Status) {
+	x.v2 = *st
+}