Use internal dz messages to process duration and location changes
Add world DynamicZone class (later this will inherit from a base)
Add FindDynamicZoneByID to get dz from zone and world system caches
This exposes dynamic zone ids for any future changes and will make it
easier to preserve historic dz and expedition data. This also cleans up
some dynamic zone creation for expedition requests
When purging instances the expedition table is no longer updated
since dynamic zone ids are not re-used like instance ids are
Update #dz list commands to show dz id
Add GetDynamicZoneID and get_expedition_by_dz_id quest apis
