[#1] Add object Get operation + code quality

Signed-off-by: Ivan Pchelintsev <i.pchelintsev@yadro.com>

src/FrostFS.SDK.ClientV2/Mappers/GRPC/Object.cs

@@ -52,20 +52,27 @@ public static class ObjectHeadMapper
             throw new ArgumentException($"Unknown ObjectType. Value: '{header.ObjectType}'.");
         }
 
-        var attributes = new List<ObjectAttribute>();
-        foreach (var attribute in header.Attributes)
-        {
-            attributes.Add(attribute.ToModel());
-        }
-
         return new ObjectHeader(
             ContainerId.FromHash(header.ContainerId.Value.ToByteArray()),
             Enum.Parse<ModelsV2.Enums.ObjectType>(objTypeName),
-            attributes.ToArray()
+            header.Attributes.Select(attribute => attribute.ToModel()).ToArray()
         )
         {
             Size = (long)header.PayloadLength,
             Version = header.Version.ToModel()
         };
     }
+}
+
+public static class ObjectMapper
+{
+    public static ModelsV2.Object ToModel(this Object.Object obj)
+    {
+        return new ModelsV2.Object
+        {
+            Header = obj.Header.ToModel(),
+            ObjectId = ObjectId.FromHash(obj.ObjectId.Value.ToByteArray()),
+            Payload = obj.Payload.ToByteArray()
+        };
+    }
 }