[Zones] Convert IDLE_WHEN_EMPTY to a Zone Column (#3891)

* [Rules] Convert IDLE_WHEN_EMPTY to a rule

# Notes
- Converts `IDLE_WHEN_EMPTY` to `Zone:ZonesIdleWhenEmpty` so that we can change this on the fly or on a zone-by-zone basis instead of having to recompile to do this.
- Especially helpful for those using release binaries that do not compile their own source.

* Convert to zone column.

* Update ruletypes.h

* Update ruletypes.h

* Update entity.cpp

* Update entity.cpp

* Rename.

* Update database_update_manifest.cpp

* Update base_zone_repository.h

* Update zone.cpp

* seconds_before_idle

* Update database_update_manifest.cpp

* Getter/Setters/Private

* Update base_zone_repository.h

* IsIdle()/SetIsIdle()

* Update entity.cpp

zone/zone.h

@@ -105,7 +105,12 @@ public:
 	AA::Ability *GetAlternateAdvancementAbilityByRank(int rank_id);
 	AA::Rank *GetAlternateAdvancementRank(int rank_id);
 	bool is_zone_time_localized;
-	bool process_mobs_while_empty;
+	bool IsIdle() const;
+	void SetIsIdle(bool m_is_idle);
+	bool IsIdleWhenEmpty() const;
+	void SetIdleWhenEmpty(bool idle_when_empty);
+	uint32 GetSecondsBeforeIdle() const;
+	void SetSecondsBeforeIdle(uint32 seconds_before_idle);
 	bool AggroLimitReached() { return (aggroedmobs > 10) ? true : false; }
 	bool AllowMercs() const { return (allow_mercs); }
 	bool CanBind() const { return (can_bind); }
@@ -436,6 +441,9 @@ private:
 	uint32    m_max_clients;
 	uint32    zoneid;
 	uint32    m_last_ucss_update;
+	bool      m_idle_when_empty;
+	uint32    m_seconds_before_idle;
+	bool      m_is_idle;
 
 	GlobalLootManager                   m_global_loot;
 	LinkedList<ZoneClientAuth_Struct *> client_auth_list;