[#64] object: move package from neofs-api-go

Also, remove deprecated method.

Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>

object/error.go

@@ -0,0 +1,19 @@
+package object
+
+type SplitInfoError struct {
+	si *SplitInfo
+}
+
+const splitInfoErrorMsg = "object not found, split info has been provided"
+
+func (s *SplitInfoError) Error() string {
+	return splitInfoErrorMsg
+}
+
+func (s *SplitInfoError) SplitInfo() *SplitInfo {
+	return s.si
+}
+
+func NewSplitInfoError(v *SplitInfo) *SplitInfoError {
+	return &SplitInfoError{si: v}
+}