chore(content): Cleans up abilities and some spell timers (#427)

- [X] Exposes Index/Count on the timer.
- [X] Cleans up abilities
- [X] Combines some spell context/info objects with their timers to reduce allocations
- [X] Fixes a bug where immolating weapon both finishes effect or stops in the wrong order due to a race condition.

Projects/UOContent/Items/Weapons/Abilities/WhirlwindAttack.cs

@@ -14,7 +14,7 @@ namespace Server.Items
 
         public override void OnHit(Mobile attacker, Mobile defender, int damage)
         {
-            if (!Validate(attacker))
+            if (!Validate(attacker) || !CheckMana(attacker, true))
             {
                 return;
             }
@@ -33,11 +33,6 @@ namespace Server.Items
                 return;
             }
 
-            if (!CheckMana(attacker, true))
-            {
-                return;
-            }
-
             attacker.FixedEffect(0x3728, 10, 15);
             attacker.PlaySound(0x2A1);