[#1103] node: Implement Get\Head requests for EC object

Signed-off-by: Anton Nikiforov <an.nikiforov@yadro.com>

pkg/local_object_storage/util/ecinfo.go

@@ -0,0 +1,25 @@
+package util
+
+import (
+	"bytes"
+
+	objectSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
+)
+
+// MergeECInfo ignores conflicts and rewrites `to` with non empty values
+// from `from`.
+func MergeECInfo(from, to *objectSDK.ECInfo) *objectSDK.ECInfo {
+	for _, fchunk := range from.Chunks {
+		add := true
+		for _, tchunk := range to.Chunks {
+			if bytes.Equal(tchunk.ID.GetValue(), fchunk.ID.GetValue()) {
+				add = false
+				break
+			}
+		}
+		if add {
+			to.AddChunk(*objectSDK.NewECChunkFromV2(&fchunk))
+		}
+	}
+	return to
+}