fix: Removes broken OrderedHashSet and adds a simple OrderedSet (#1756)

> [!CAUTION]
> **BREAKING CHANGE**
> Removed `OrderdHashSet` and `PooledOrderedHashSet` due to bugs.

> [!NOTE]
> **Developer Note**
> The OrderedSet is not a full data structure. It is not particularly efficient. Pull Requests are welcome for a better implementation, especially if it ends up supporting `ISet<T>` and `IReadOnlySet<T>`

## Summary

The ordered hash set was buggy. It's kind of painful to implement, so for now, I added a simple `OrderedSet` to suffice for gumps. Please reach out if this causes disruption!

Projects/Server.Tests/Tests/Collections/OrderedSetTests.cs

@@ -0,0 +1,29 @@
+using Server.Collections;
+using Xunit;
+
+namespace Server.Tests;
+
+public class OrderedSetTests
+{
+    [Fact]
+    public void TestOrderedSet()
+    {
+        int[] expected = [6, 2, 4, 23, 0];
+        var set = new OrderedSet<int>();
+        for (var i = 0; i < expected.Length; i++)
+        {
+            set.Add(expected[i]);
+        }
+
+        Assert.Equal(expected.Length, set.Count);
+
+        Assert.True(set.Contains(4));
+        Assert.False(set.Contains(8));
+
+        int index = 0;
+        foreach (var value in set)
+        {
+            Assert.Equal(expected[index++], value);
+        }
+    }
+}