Core/Spells: Improved spell category cooldown handling

* Category cooldown is stored with the spell that started the cooldown (and only resetting cooldown on that spell will clear cooldowns on entire category - this fully mirrors client behavior)
* This significantly reduces the amount of data saved to database for cooldowns
* Spell casts from items that have a different category specified than on spell will now check for cooldown during the cast

(cherry picked from commit 1efb3f08e278530f59d681f676b031a7fc6db3ac)

Closes #15766
Closes #15137
Closes #14837

src/server/game/Spells/Spell.cpp

@@ -4668,7 +4668,7 @@ SpellCastResult Spell::CheckCast(bool strict)
                 return SPELL_FAILED_NOT_READY;
         }
 
-        if (!m_caster->GetSpellHistory()->IsReady(m_spellInfo))
+        if (!m_caster->GetSpellHistory()->IsReady(m_spellInfo, m_castItemEntry))
         {
             if (m_triggeredByAuraSpell)
                 return SPELL_FAILED_DONT_REPORT;