[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/expedition.cpp

@@ -161,3 +161,21 @@ void Expedition::CheckLeader()
 		ChooseNewLeader();
 	}
 }
+
+bool Expedition::Process()
+{
+	// returns true if expedition needs to be deleted from world cache and db
+	// expedition is not deleted until its dz has no clients to prevent exploits
+	auto status = m_dynamic_zone.Process(IsEmpty()); // force expire if no members
+	if (status == DynamicZoneStatus::ExpiredEmpty)
+	{
+		LogExpeditions("Expedition [{}] expired or empty, notifying zones and deleting", GetID());
+		SendZonesExpeditionDeleted();
+		return true;
+	}
+
+	CheckExpireWarning();
+	CheckLeader();
+
+	return false;
+}