In previous version of the format storage group information was stored in
completely in the dedicated header field. However, having a header field
instead of storing it in a payload is not justified, since it is used only
to check the presence in the object. Based on this, this commit defines a
message for marking the object as the custodian of information about the
storage group and changes the type of field StorageGroup to it. Information
about the storage group will be stored serialized in the payload of the
objects marked in this way
Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
67ecea7507