fix(Core/Grid): Address bugs and performance issues introduced by visibility notifier implementation (#17480)

* Bug fixes

- Corrected std::chrono from seconds to milliseconds
- Got rid of leftover code that caused objects to not show up on time

* Removed logic to set gameobject as active

- More alignement with TC.
- Reduces CPU usage drastically

* Revert back to using time_t instead of std chrono

* Invoke SetNoCreate() method to reduce CPU usage drastically

* Remove setActive from static and motion transports

* Fix performance issues

* Added SetFarVisible to WG and some dungeon scripts

- Also removed setActive(true) from creatures in Wintergrasp. As for gameobjects they are set to active upon being damaged/destroyed and removed from active on rebuild (reset)

* Removed comments related to VISIBILITY_COMPENSATION

* Fix log

* Deleted unused files + corrected a check

* Added missing header

* Removed unused parameter

* Removed another unsued parameter

* Changed vector to set for i_visibleNow

- Changed vector to set for i_visibleNow in VisibleNotifer
- Adjusted HaveAtClient to accept Object*
- Adjusted SendUpdateToPlayer to send createobject packet only if not known to client

src/server/game/Grids/ObjectGridLoader.cpp

@@ -25,6 +25,7 @@
 #include "ObjectMgr.h"
 #include "Transport.h"
 #include "Vehicle.h"
+#include "GameTime.h"
 
 void ObjectGridEvacuator::Visit(CreatureMapType& m)
 {
@@ -113,18 +114,6 @@ void AddObjectHelper(CellCoord& cell, CreatureMapType& m, uint32& count, Map* ma
     ++count;
 }
 
-template <>
-void AddObjectHelper(CellCoord& cell, GameObjectMapType& m, uint32& count, Map* map, GameObject* obj)
-{
-    obj->AddToGrid(m);
-    ObjectGridLoader::SetObjectCell(obj, cell);
-    obj->AddToWorld();
-    if (obj->isActiveObject())
-        map->AddToActive(obj);
-
-    ++count;
-}
-
 template <class T>
 void LoadHelper(CellGuidSet const& /*guid_set*/, CellCoord& /*cell*/, GridRefMgr<T>& /*m*/, uint32& /*count*/, Map* /*map*/)
 {
@@ -135,8 +124,13 @@ void LoadHelper(CellGuidSet const& guid_set, CellCoord& cell, GridRefMgr<Creatur
 {
     for (CellGuidSet::const_iterator i_guid = guid_set.begin(); i_guid != guid_set.end(); ++i_guid)
     {
-        Creature* obj = new Creature();
+        // Don't spawn at all if there's a respawn timer
         ObjectGuid::LowType guid = *i_guid;
+        time_t now = GameTime::GetGameTime().count();
+        if (map->GetCreatureRespawnTime(guid) > now)
+            continue;
+
+        Creature* obj = new Creature();
         if (!obj->LoadFromDB(guid, map))
         {
             delete obj;
@@ -162,7 +156,12 @@ void LoadHelper(CellGuidSet const& guid_set, CellCoord& cell, GridRefMgr<GameObj
 {
     for (CellGuidSet::const_iterator i_guid = guid_set.begin(); i_guid != guid_set.end(); ++i_guid)
     {
+        // Don't spawn at all if there's a respawn timer
         ObjectGuid::LowType guid = *i_guid;
+        time_t now = GameTime::GetGameTime().count();
+        if (map->GetGORespawnTime(guid) > now)
+            continue;
+
         GameObjectData const* data = sObjectMgr->GetGameObjectData(guid);
         GameObject* obj = data && sObjectMgr->IsGameObjectStaticTransport(data->id) ? new StaticTransport() : new GameObject();