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/Server/Buffers/SpanReader.cs

@@ -31,6 +31,8 @@ public ref struct SpanReader
     public int Position { get; private set; }
     public int Remaining => Length - Position;
 
+    public ReadOnlySpan<byte> Buffer => _buffer;
+
     public SpanReader(ReadOnlySpan<byte> span)
     {
         _buffer = span;
@@ -184,13 +186,13 @@ public ref struct SpanReader
         {
             // In case the remaining is not evenly divisible
             size = remaining - (remaining & (byteLength - 1));
-            int index = _buffer.Slice(Position, size).IndexOfTerminator(byteLength);
-            size = index < 0 ? size : index;
         }
 
         var span = _buffer.Slice(Position, size);
-        Position += size;
-        return TextEncoding.GetString(span, encoding, safeString);
+        var index = span.IndexOfTerminator(byteLength);
+
+        Position += isFixedLength || index < 0 ? size : index;
+        return TextEncoding.GetString(span[..index], encoding, safeString);
     }
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]