[Zone] Implement Zone State Saving on Shutdown (#4715)

* Save spawns

* Update base_zone_state_spawns_repository.h

* Zone state save work

* Code cleanup

* More cleanup

* Database migration

* Update database_update_manifest.cpp

* Revert decay at storage model

* Code cleanup

* More cleanup

* More cleanup

* More cleanup

* Entity variables

* Add entity variables to the schema

* Post rebase

* Checkpoint

* Serialize / deserialize buffs

* Current hp / mana / end save / load

* Save / load current_waypoint

* Add zone spawn protection

* Finishing touches

* Cleanup

* Update zone_save_state.cpp

* Cleanup

* Update zone_save_state.cpp

* Update npc.cpp

* Update npc.cpp

* More

* Update perl_npc.cpp

* Update zone_loot.cpp

zone/npc.h

@@ -601,6 +601,13 @@ public:
 	bool HasProcessedHandinReturn() { return m_has_processed_handin_return; }
 	bool HandinStarted() { return m_handin_started; }
 
+	// zone state save
+	inline void SetQueuedToCorpse() { m_queued_for_corpse = true; }
+	inline bool IsQueuedForCorpse() { return m_queued_for_corpse; }
+	inline uint32_t SetCorpseDecayTime(uint32_t decay_time) { return m_corpse_decay_time = decay_time; }
+	inline void SetResumedFromZoneSuspend(bool state = true) { m_resumed_from_zone_suspend = state; }
+	inline bool IsResumedFromZoneSuspend() { return m_resumed_from_zone_suspend; }
+
 protected:
 
 	void HandleRoambox();
@@ -622,6 +629,18 @@ protected:
 	uint32    m_loot_platinum;
 	LootItems m_loot_items;
 
+	// zone state
+	bool     m_resumed_from_zone_suspend  = false;
+	bool     m_queued_for_corpse          = false; // this is to check for corpse creation on zone state restore
+	uint32_t m_corpse_decay_time          = 0; // decay time set on zone state restore
+	Timer    m_corpse_queue_timer         = {}; // this is to check for corpse creation on zone state restore
+	Timer    m_corpse_queue_shutoff_timer = {};
+
+	// this is a 30-second timer that protects a NPC from having double assignment of loot
+	// this is to prevent a player from killing a NPC and then zoning out and back in to get loot again
+	// if loot was to be assigned via script again, this protects double assignment for 30 seconds
+	Timer m_resumed_from_zone_suspend_shutoff_timer = {};
+
 	std::list<NpcFactionEntriesRepository::NpcFactionEntries> faction_list;
 
 	int32	npc_faction_id;