[#31] refs: Define OwnerID message

Define OwnerID message in refs package. In the future, this structure can be
ported into messages in place of the owner identifier field to maintain format
uniformity. Also, storing the identifier in a dedicated message will allow, if
necessary, to expand it with additional information without losing backward
compatibility within one version of the API.

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

proto-docs/refs.md

@@ -9,6 +9,7 @@
     - [Address](#refs.Address)
     - [ContainerID](#refs.ContainerID)
     - [ObjectID](#refs.ObjectID)
+    - [OwnerID](#refs.OwnerID)
     
 
 - [Scalar Value Types](#scalar-value-types)
@@ -57,6 +58,17 @@ ObjectID groups information about the NeoFS object identifier.
 | ----- | ---- | ----- | ----------- |
 | Value | [bytes](#bytes) |  | Value carries the object identifier in a binary format. |
 
+
+<a name="refs.OwnerID"></a>
+
+### Message OwnerID
+OwnerID group information about the owner of the NeoFS container.
+
+
+| Field | Type | Label | Description |
+| ----- | ---- | ----- | ----------- |
+| Value | [bytes](#bytes) |  | Value carries the identifier of the container owner in a binary format. |
+
  <!-- end messages -->
 
  <!-- end enums -->

refs/types.proto

@@ -29,3 +29,9 @@ message ContainerID {
     // Value carries the container identifier in a binary format.
     bytes Value = 1;
 }
+
+// OwnerID group information about the owner of the NeoFS container.
+message OwnerID {
+    // Value carries the identifier of the container owner in a binary format.
+    bytes Value = 1;
+}