Flow statistics model do not have a notion of a multi-part transaction

The way the various statistics notifications are modeled is that they each define a moreReplies leaf:

notification flows-statistics-update {
description "Flows statistics sent by switch";
leaf moreReplies

{ type boolean; }

uses inv:node;
uses flow-and-statistics-map-list;
uses tr:transaction-aware;
}

now this makes it quite clunky in the stats manager code, where each instantiation needs to pass that one bit down. Correct way of doing this would be to introduce a multipart-transaction-aware concepts:

grouping multipart-transaction-aware {
uses tr:transaction-aware;
leaf moreReplies

{ type boolean; default false; }

}

and use that in the stats, like this:

notification flows-statistics-update

{ description "Flows statistics sent by switch"; uses inv:node; uses flow-and-statistics-map-list; uses tr:multipart-transaction-aware; }