Core/Units: Power handling improvements

* Don't include creature_template power multipliers in CreateMana updatefield
* Allow NPCs to have power types other than mana
* Add missing Essence config regeneration rate
* Fixed demon hunter powers not decaying immediately after combat
* Fixed some powers decaying immediately out of combat after energizing (for example holy power)
* Replace hardcoded list of powers to set to full on levelup with a db2 flag check
* Updated Creature::GetPowerIndex for 10.1 new power types
Port From (https://github.com/TrinityCore/TrinityCore/commit/1325e0c4b279d590acbcbb05d6abdf5fdb66a882)

Source/Game/Entities/Unit/Unit.Spells.cs

@@ -1172,6 +1172,15 @@ namespace Game.Entities
 
         public void EnergizeBySpell(Unit victim, SpellInfo spellInfo, int damage, PowerType powerType)
         {
+            Player player = victim.ToPlayer();
+            if (player != null)
+            {
+                var powerTypeEntry = Global.DB2Mgr.GetPowerTypeEntry(powerType);
+                if (powerTypeEntry != null)
+                    if (powerTypeEntry.GetFlags().HasFlag(PowerTypeFlags.UseRegenInterrupt))
+                        player.InterruptPowerRegen(powerType);
+            }
+
             int gain = victim.ModifyPower(powerType, damage, false);
             int overEnergize = damage - gain;