Core/Spells: Define all spell modifier types and implement ProcCooldown mod and PeriodicHealingAndDamage for melee periodic damage

Port From (https://github.com/TrinityCore/TrinityCore/commit/6585666e6e34ade0333e4c23876acdf847d169c0)

Source/Game/Combat/ThreatManager.cs

@@ -352,7 +352,7 @@ namespace Game.Combat
 
                 Player modOwner = hatedUnit.GetSpellModOwner();
                 if (modOwner != null)
-                    modOwner.ApplySpellMod(threatSpell, SpellModOp.Threat, ref threat);
+                    modOwner.ApplySpellMod(threatSpell, SpellModOp.Hate, ref threat);
             }
 
             return hatedUnit.ApplyTotalThreatModifier(threat, schoolMask);