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.Tests/Tests/Network/Packets/Outgoing/MapPacketTests.cs

@@ -15,8 +15,8 @@ namespace Server.Tests.Network
 
             ns.SendMapPatches();
 
-            var result = ns.SendPipe.Reader.TryRead();
-            AssertThat.Equal(result.Buffer[0].AsSpan(0), expected);
+            var result = ns.SendPipe.Reader.AvailableToRead();
+            AssertThat.Equal(result, expected);
         }
 
         [Fact]
@@ -27,8 +27,8 @@ namespace Server.Tests.Network
             var ns = PacketTestUtilities.CreateTestNetState();
             ns.SendInvalidMap();
 
-            var result = ns.SendPipe.Reader.TryRead();
-            AssertThat.Equal(result.Buffer[0].AsSpan(0), expected);
+            var result = ns.SendPipe.Reader.AvailableToRead();
+            AssertThat.Equal(result, expected);
         }
 
         [Theory]
@@ -42,8 +42,8 @@ namespace Server.Tests.Network
             var ns = PacketTestUtilities.CreateTestNetState();
             ns.SendMapChange(map);
 
-            var result = ns.SendPipe.Reader.TryRead();
-            AssertThat.Equal(result.Buffer[0].AsSpan(0), expected);
+            var result = ns.SendPipe.Reader.AvailableToRead();
+            AssertThat.Equal(result, expected);
         }
     }
 }