Split the two command implementations into separate libraries (#2012)

This will allow us at the user code side to determine to include old commands, new commands or both.

wpilibNewCommands/src/test/native/cpp/frc2/command/ErrorConfirmer.h

@@ -0,0 +1,42 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2019 FIRST. All Rights Reserved.                             */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#pragma once
+
+#include <regex>
+
+#include <mockdata/MockHooks.h>
+
+#include "gmock/gmock.h"
+#include "simulation/DriverStationSim.h"
+
+class ErrorConfirmer {
+ public:
+  explicit ErrorConfirmer(const char* msg) : m_msg(msg) {
+    if (instance != nullptr) return;
+    HALSIM_SetSendError(HandleError);
+    EXPECT_CALL(*this, ConfirmError());
+    instance = this;
+  }
+
+  ~ErrorConfirmer() {
+    HALSIM_SetSendError(nullptr);
+    instance = nullptr;
+  }
+
+  MOCK_METHOD0(ConfirmError, void());
+
+  const char* m_msg;
+
+  static int32_t HandleError(HAL_Bool isError, int32_t errorCode,
+                             HAL_Bool isLVCode, const char* details,
+                             const char* location, const char* callStack,
+                             HAL_Bool printMsg);
+
+ private:
+  static ErrorConfirmer* instance;
+};