feat: Adds a memory mirrored ring buffer for networking. (#1533)

## Breaking Changes

Incoming packet registration signature has changed to:
```cs
delegate* void OnReceiveCallback(NetState state, SpanReader reader, int packetLength);

IncomingPackets.Register(int packetID, int length, bool ingame, OnReceiveCallback onReceive);
```

For example, an incoming packet handler signature would now look like this:
```cs
public static void SomeIncomingPacket(NetState state, SpanReader reader, int packetLength)
{
    // Parse the data
}
```

## Summary

Updates the network Pipe class to use a mirrored memory technique. This technique involves mapping the same physical memory to two contiguous virtual memory spaces so the byte buffer appears duplicated. This allows writing to a double-sized array to wrap around without the need for the `CircularBuffer` classes.

In practice this allows us to use `Span<byte>` as if the buffer was a regular array.


### Bug Fixes

- [X] Fixes bad fixed length string parsing

Projects/UOContent/Engines/UltimaStore/UltimaStorePackets.cs

@@ -1,3 +1,4 @@
+using System.Buffers;
 using Server.Network;
 
 namespace Server.Engines.UltimaStore
@@ -9,7 +10,7 @@ namespace Server.Engines.UltimaStore
             IncomingPackets.Register(0xFA, 1, true, &UltimaStoreOpenRequest);
         }
 
-        public static void UltimaStoreOpenRequest(NetState state, CircularBufferReader reader, int packetLength)
+        public static void UltimaStoreOpenRequest(NetState state, SpanReader reader, int packetLength)
         {
             state.Mobile.SendMessage("Ultima Store is not currently available.");
         }