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/main/native/include/frc2/command/StartEndCommand.h

@@ -0,0 +1,46 @@
+/*----------------------------------------------------------------------------*/
+/* 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 "CommandBase.h"
+#include "CommandHelper.h"
+
+namespace frc2 {
+/**
+ * A command that runs a given runnable when it is initalized, and another
+ * runnable when it ends. Useful for running and then stopping a motor, or
+ * extending and then retracting a solenoid. Has no end condition as-is; either
+ * subclass it or use Command.WithTimeout() or Command.WithInterrupt() to give
+ * it one.
+ */
+class StartEndCommand : public CommandHelper<CommandBase, StartEndCommand> {
+ public:
+  /**
+   * Creates a new StartEndCommand.  Will run the given runnables when the
+   * command starts and when it ends.
+   *
+   * @param onInit       the Runnable to run on command init
+   * @param onEnd        the Runnable to run on command end
+   * @param requirements the subsystems required by this command
+   */
+  StartEndCommand(std::function<void()> onInit, std::function<void()> onEnd,
+                  std::initializer_list<Subsystem*> requirements);
+
+  StartEndCommand(StartEndCommand&& other) = default;
+
+  StartEndCommand(const StartEndCommand& other);
+
+  void Initialize() override;
+
+  void End(bool interrupted) override;
+
+ protected:
+  std::function<void()> m_onInit;
+  std::function<void()> m_onEnd;
+};
+}  // namespace frc2