Draft: Use catalog zones' member zones count when calculating zone mem/task pool sizes

Currently named does not take into account the catalog zones' member zones count when calculating the sizes of the zone mem/task pools.

Create a function in catz.c to calculate the member zones in all catalog zones in the collection, and use that in named when counting the number of all zones.

Create a new event for named which will be generated by catz.c after a successful catalog zone post-update merge, which will adjust (if needed) the sizes of zone mem/task pools based on the difference of member zones count in the previous and current versions of the catalog zone.

Closes #3159 (closed)