[sim] Add XRP-specific plugin (#5631)

Provides an implementation of a XRP-specific plugin that sends binary messages over UDP (to account for the less performant hardware on the XRP).

This plugin leverages the work already done for the WebSocket protocol and does a translation to/from JSON/binary.

simulation/halsim_xrp/src/main/native/cpp/main.cpp

@@ -0,0 +1,42 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+#include <cstdio>
+#include <memory>
+
+#include <hal/Extensions.h>
+
+#include "HALSimXRPClient.h"
+
+#if defined(Win32) || defined(_WIN32)
+#pragma comment(lib, "Ws2_32.lib")
+#endif
+
+using namespace wpilibxrp;
+
+static std::unique_ptr<HALSimXRPClient> gClient;
+
+/*--------------------------------------------------------------------------
+** Main Entry Point. Start up the listening threads
+**------------------------------------------------------------------------*/
+extern "C" {
+#if defined(WIN32) || defined(_WIN32)
+__declspec(dllexport)
+#endif
+
+    int HALSIM_InitExtension(void) {
+  std::puts("HALSim XRP Extension Initializing");
+
+  HAL_OnShutdown(nullptr, [](void*) { gClient.reset(); });
+
+  gClient = std::make_unique<HALSimXRPClient>();
+  if (!gClient->Initialize()) {
+    return -1;
+  }
+
+  std::puts("HALSim XRP Extention Initialized");
+  return 0;
+}
+
+}  // extern "C"