tipc: Separate cluster-scope and zone-scope names into distinct lists

Utilizes distinct lists to track zone-scope and cluster-scope names
published by a node. For now, TIPC continues to process the entries
in both lists in the same way; however, an upcoming patch will utilize
the existence of the lists to prevent the sending of cluster-scope names
to nodes that are not part of the local cluster.

To achieve this, an array of publication lists is introduced, so
that they can be iterated over and accessed via publ->scope as
an index where convenient.

Signed-off-by: Allan Stephens <allan.stephens@windriver.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>