fix: Optimize OrderedHashSet and introduce more high perf collections (#679)

* Optimizes OrderedHashSet using the learnings here: https://github.com/dotnet/runtime/issues/10050
* Removes ValueCollection since it was a relic from the conversion of the OrderedDictionary
* Centralizes throw strings.
* Adds pooled ordered hash set (but doesn't use it)

Closes #448

Projects/Benchmarks/Benchmarks/Packets/PacketTestUtilities.cs

@@ -2,11 +2,15 @@ using System;
 using System.Buffers.Binary;
 using System.Runtime.CompilerServices;
 using Server;
+using Server.Network;
 
 namespace Benchmarks
 {
     public static class PacketTestUtilities
     {
+        public static Span<byte> Compile(this Packet p) =>
+            p.Compile(false, out var length).AsSpan(0, length);
+
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static void Write(this Span<byte> data, ref int pos, Serial serial)
         {