[#1383] object: Add restrictions for Patch method

* `Patch` can't be applied for non-regular type object (tombstones,
  locks etc.)
* Complex object parts can't be patched. So, if an object has EC/Split
  header, it won't be patched.

Signed-off-by: Airat Arifullin <a.arifullin@yadro.com>

pkg/services/object/patch/streamer.go

@@ -63,6 +63,14 @@ func (s *Streamer) init(ctx context.Context, req *objectV2.PatchRequest) error {
 		return err
 	}
 
+	if hdrWithSig.GetHeader().GetObjectType() != objectV2.TypeRegular {
+		return errors.New("non-regular object can't be patched")
+	}
+
+	if hdrWithSig.GetHeader().GetEC() != nil || hdrWithSig.GetHeader().GetSplit() != nil {
+		return errors.New("complex object parts can't be patched")
+	}
+
 	commonPrm, err := util.CommonPrmFromV2(req)
 	if err != nil {
 		return err