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/ScheduleCommandTest.cpp

@@ -0,0 +1,32 @@
+/*----------------------------------------------------------------------------*/
+/* 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.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include <regex>
+
+#include "CommandTestBase.h"
+#include "frc2/command/InstantCommand.h"
+#include "frc2/command/ScheduleCommand.h"
+#include "frc2/command/SequentialCommandGroup.h"
+
+using namespace frc2;
+class ScheduleCommandTest : public CommandTestBase {};
+
+TEST_F(ScheduleCommandTest, ScheduleCommandScheduleTest) {
+  CommandScheduler& scheduler = CommandScheduler::GetInstance();
+
+  bool scheduled = false;
+
+  InstantCommand toSchedule([&scheduled] { scheduled = true; }, {});
+
+  ScheduleCommand command(&toSchedule);
+
+  scheduler.Schedule(&command);
+  scheduler.Run();
+
+  EXPECT_TRUE(scheduled);
+  EXPECT_FALSE(scheduler.IsScheduled(&command));
+}