Core/Items: Implement azerite essences

Port From (https://github.com/TrinityCore/TrinityCore/commit/ec9d624aec9e0a39b1bcee7d4077f46be358faad)

Source/Framework/Constants/CliDBConst.cs

@@ -923,6 +923,13 @@ namespace Framework.Constants
         First = NoLinkRequired | DontCountFirstBonusRank,
     }
 
+    public enum AzeriteItemMilestoneType
+    {
+        MajorEssence = 0,
+        MinorEssence = 1,
+        BonusStamina = 2
+    }
+
     public enum BattlegroundBracketId                                  // bracketId for level ranges
     {
         First = 0,

Source/Framework/Constants/ItemConst.cs

@@ -1170,4 +1170,20 @@ namespace Framework.Constants
 
         Invalid
     }
+
+    public enum AzeriteEssenceActivateResult
+    {
+        None = 0,
+        EssenceNotUnlocked = 2,    // Arg: AzeriteEssenceID
+        CantDoThatRightNow = 3,
+        AffectingCombat = 4,
+        CantRemoveEssence = 5,    // Arg: SpellID of active essence on cooldown
+        ChallengeModeActive = 6,
+        NotInRestArea = 7,
+        ConditionFailed = 8,
+        SlotLocked = 9,
+        NotAtForge = 10,
+        HeartLevelTooLow = 11,   // Arg: RequiredLevel
+        NotEquipped = 12
+    }
 }

Source/Framework/Constants/PlayerConst.cs

@@ -69,6 +69,8 @@ namespace Framework.Constants
         public const uint ItemIdHeartOfAzeroth = 158075;
         public const uint MaxAzeriteItemLevel = 70;
         public const uint MaxAzeriteItemKnowledgeLevel = 30;
+        public const uint PlayerConditionIdUnlockedAzeriteEssences = 69048;
+        public const uint SpellIdHeartEssenceActionBarOverride = 298554;
     }
 
     public struct MoneyConstants

Source/Framework/Constants/SharedConst.cs

@@ -40,6 +40,8 @@ namespace Framework.Constants
         public const int MaxWorldMapOverlayArea = 4;
         public const int MaxMountCapabilities = 24;
         public const int MaxLockCase = 8;
+        public const int MaxAzeriteEssenceSlot = 3;
+        public const int MaxAzeriteEssenceRank = 4;
 
         /// <summary>
         /// BattlePets Const