fix: Optimizes FindItemsByType by removing allocations. (#1515)

### Summary
Container enumeration is in dire need of optimization. Thanks to @stefanomerotta for initiating this work with PR #1443. This PR handles a small part of what Stefan started. Also included are some bug fixes.

### Method Signatures

```cs
// Use with foreach without moving/deleting items
FindItemsByTypeEnumerator<T> FindItemsByType<T>(bool recurse = true, Predicate<T> predicate = null)

// Use with foreach when moving/deleting items
QueuedItemsEnumerator<T> EnumerateItemsByType<T>(bool recurse = true, Predicate<T> predicate = null)

// Use when iterating multiple times or queuing
PooledRefQueue<T> QueueItemsByType<T>(bool recurse = true, Predicate<T> predicate = null)

// Use when iterating multiples times or manipulating elements without traversing
PooledRefList<T> ListItemsByType<T>(bool recurse = true, Predicate<T> predicate = null)
```

* `FindItemsByType<T>` has changed from returning `List<T>` to `FindItemsByTypeEnumerator<T>` - This method is not safe to use in situations where an item may get consumed, deleted, or moved.

* `EnumerateItemsByType<T>` was added as a safe way to iterate and manipulate items.
  * **Note**: EnumerateItemsByType will _completely traverse the container_ before iteration starts because it uses `QueueItemsByType` under the hood.

* `QueueItemsByType<T>`  and `ListItemsByType<T>` was added to return a queue or list of items to iterate multiple times and manipulate the items. This isn't the most efficient since it uses a predicate and can result in 2 or 3 total iterations unnecessarily.

### Bug Fixes
- [X] Fishing had an error in the random check that may have caused slight bias.

Projects/UOContent/Mobiles/PlayerMobile.cs

@@ -2393,9 +2393,14 @@ namespace Server.Mobiles
 
             DropHolding();
 
+            // During AOS+, insured/blessed items are moved out of their child containers and put directly into the backpack.
+            // This fixes a "bug" where players put blessed items in nested bags and they were dropped on death
             if (Core.AOS && Backpack?.Deleted == false)
             {
-                Backpack.FindItemsByType<Item>(FindItems_Callback).ForEach(item => Backpack.AddItem(item));
+                foreach (var item in Backpack.EnumerateItemsByType<Item>(predicate: FindItems_Callback))
+                {
+                    Backpack.AddItem(item);
+                }
             }
 
             EquipSnapshot = new List<Item>(Items);
@@ -3910,13 +3915,13 @@ namespace Server.Mobiles
                 return;
             }
 
-            var items = new List<Item>();
+            using var queue = PooledRefQueue<Item>.Create(128);
 
             foreach (var item in Items)
             {
                 if (DisplayInItemInsuranceGump(item))
                 {
-                    items.Add(item);
+                    queue.Enqueue(item);
                 }
             }
 
@@ -3924,20 +3929,26 @@ namespace Server.Mobiles
 
             if (pack != null)
             {
-                items.AddRange(pack.FindItemsByType<Item>(DisplayInItemInsuranceGump));
+                foreach (var item in pack.FindItemsByType())
+                {
+                    if (DisplayInItemInsuranceGump(item))
+                    {
+                        queue.Enqueue(item);
+                    }
+                }
             }
 
             // TODO: Investigate item sorting
 
             CloseGump<ItemInsuranceMenuGump>();
 
-            if (items.Count == 0)
+            if (queue.Count == 0)
             {
                 SendLocalizedMessage(1114915, "", 0x35); // None of your current items meet the requirements for insurance.
             }
             else
             {
-                SendGump(new ItemInsuranceMenuGump(this, items.ToArray()));
+                SendGump(new ItemInsuranceMenuGump(this, queue.ToArray()));
             }
         }
 

Projects/UOContent/Mobiles/Townfolk/Banker.cs

@@ -1,6 +1,5 @@
 using System;
 using System.Collections.Generic;
-using System.Linq;
 using Server.Accounting;
 using Server.ContextMenus;
 using Server.Items;
@@ -47,32 +46,36 @@ namespace Server.Mobiles
 
             if (bank != null)
             {
-                var gold = bank.FindItemsByType<Gold>();
-                var checks = bank.FindItemsByType<BankCheck>();
+                foreach (var gold in bank.FindItemsByType<Gold>())
+                {
+                    balance += gold.Amount;
+                }
 
-                balance += gold.Aggregate(0L, (c, t) => c + t.Amount);
                 if (balance >= int.MaxValue)
                 {
                     return int.MaxValue;
                 }
 
-                balance += checks.Aggregate(0L, (c, t) => c + t.Worth);
+                foreach (var check in bank.FindItemsByType<BankCheck>())
+                {
+                    balance += check.Worth;
+                }
             }
 
-            return Math.Max(0, (int)Math.Min(int.MaxValue, balance));
+            return (int)Math.Clamp(balance, 0, int.MaxValue);
         }
 
         public static int GetBalance(Mobile m, out List<Item> gold, out List<Item> checks)
         {
             long balance = 0;
+            gold = checks = new List<Item>();
 
             if (AccountGold.Enabled && m.Account != null)
             {
                 balance = m.Account.GetTotalGold();
 
-                if (balance > int.MaxValue)
+                if (balance >= int.MaxValue)
                 {
-                    gold = checks = new List<Item>();
                     return int.MaxValue;
                 }
             }
@@ -81,23 +84,25 @@ namespace Server.Mobiles
 
             if (bank != null)
             {
-                gold = bank.FindItemsByType(typeof(Gold));
-                checks = bank.FindItemsByType(typeof(BankCheck));
+                foreach (var g in bank.FindItemsByType<Gold>())
+                {
+                    balance += g.Amount;
+                    gold.Add(g);
+                }
 
-                balance += gold.OfType<Gold>().Aggregate(0L, (c, t) => c + t.Amount);
                 if (balance >= int.MaxValue)
                 {
                     return int.MaxValue;
                 }
 
-                balance += checks.OfType<BankCheck>().Aggregate(0L, (c, t) => c + t.Worth);
-            }
-            else
-            {
-                gold = checks = new List<Item>();
+                foreach (var bc in bank.FindItemsByType<BankCheck>())
+                {
+                    balance += bc.Worth;
+                    checks.Add(bc);
+                }
             }
 
-            return Math.Max(0, (int)Math.Min(int.MaxValue, balance));
+            return (int)Math.Clamp(balance, 0, int.MaxValue);
         }
 
         public static bool Withdraw(Mobile from, int amount)