This creates an abstract class in common so zone and world can share
most of the implementation. World now has access to the same dz data and
api as zone.
Rename CharacterChange to AddRemoveCharacter for clarity
Rename GetRemainingDuration to GetDurationRemaining for consistency
Move dynamic zone queries to custom repository methods
Move early empty shutdown and process rate rules to DynamicZone scope
This decouples the expired status check from expeditions into an
internal dz method that can be called by its owning system
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
