[Expeditions] Let dz process its expired state (#1310)

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

world/dynamic_zone.h

@@ -6,6 +6,14 @@
 
 class ServerPacket;
 
+enum class DynamicZoneStatus
+{
+	Unknown = 0,
+	Normal,
+	Expired,
+	ExpiredEmpty,
+};
+
 class DynamicZone
 {
 public:
@@ -23,6 +31,7 @@ public:
 	std::chrono::system_clock::duration GetRemainingDuration() const {
 		return m_expire_time - std::chrono::system_clock::now(); }
 
+	DynamicZoneStatus Process(bool force_expire);
 	bool IsExpired() const { return m_expire_time < std::chrono::system_clock::now(); }
 	void SetSecondsRemaining(uint32_t seconds_remaining);
 
@@ -33,6 +42,7 @@ private:
 	uint32_t m_instance_id = 0;
 	uint32_t m_zone_id = 0;
 	uint32_t m_zone_version = 0;
+	bool m_is_pending_early_shutdown = false;
 	DynamicZoneType m_type{ DynamicZoneType::None };
 	std::chrono::seconds m_duration;
 	std::chrono::time_point<std::chrono::system_clock> m_start_time;