fix: Changes Map.Sector.Mobiles to link list & Fixes various related crash bugs (#1553)

### Summary

Eliminates `IPooledEnumerable<T>` and `eable.Free()` from `Map` for mobiles. This drastically simplifies code that iterates in range, for example:

```cs
foreach (var m in m.GetMobilesInRange(5))
{
}
```
The code above no longer requires an eable and calling `Free()`.

- [X] Fixed several locations where an NPC that was damaged would cause a server crash.
- [X] Removed an unnecessary allocation in guard fake calls (NPCs calling guards on you)
- [X] Fixes damage precision loss in Poison Strike Spell
- [X] BogThing no longer attempts to "search" for boglings to eat when it is at full health

Projects/UOContent/Spells/Necromancy/Wither.cs

@@ -51,8 +51,7 @@ namespace Server.Spells.Necromancy
                     var cbc = Caster as BaseCreature;
                     var isMonster = cbc?.Controlled == false && (cbc.IsAnimatedDead || !cbc.Summoned);
 
-                    var eable = Caster.GetMobilesInRange(Core.ML ? 4 : 5);
-                    foreach (var targ in eable)
+                    foreach (var targ in Caster.GetMobilesInRange(Core.ML ? 4 : 5))
                     {
                         if (targ == Caster
                             || !Caster.InLOS(targ)
@@ -106,7 +105,7 @@ namespace Server.Spells.Necromancy
 
                         double damage = Utility.RandomMinMax(30, 35);
 
-                        damage *= 300 + m.Karma / 100 + GetDamageSkill(Caster) * 10;
+                        damage *= 300 + m.Karma / 100.0 + GetDamageSkill(Caster) * 10;
                         damage /= 1000;
 
                         var sdiBonus = AosAttributes.GetValue(Caster, AosAttribute.SpellDamage);