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/ProxyScheduleCommand.h

@@ -0,0 +1,50 @@
+/*----------------------------------------------------------------------------*/
+/* 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 <wpi/SmallVector.h>
+
+#include "CommandBase.h"
+#include "CommandHelper.h"
+#include "SetUtilities.h"
+
+namespace frc2 {
+/**
+ * Schedules the given commands when this command is initialized, and ends when
+ * all the commands are no longer scheduled.  Useful for forking off from
+ * CommandGroups.  If this command is interrupted, it will cancel all of the
+ * commands.
+ */
+class ProxyScheduleCommand
+    : public CommandHelper<CommandBase, ProxyScheduleCommand> {
+ public:
+  /**
+   * Creates a new ProxyScheduleCommand that schedules the given commands when
+   * initialized, and ends when they are all no longer scheduled.
+   *
+   * @param toSchedule the commands to schedule
+   */
+  explicit ProxyScheduleCommand(wpi::ArrayRef<Command*> toSchedule);
+
+  ProxyScheduleCommand(ProxyScheduleCommand&& other) = default;
+
+  ProxyScheduleCommand(const ProxyScheduleCommand& other) = default;
+
+  void Initialize() override;
+
+  void End(bool interrupted) override;
+
+  void Execute() override;
+
+  bool IsFinished() override;
+
+ private:
+  wpi::SmallVector<Command*, 4> m_toSchedule;
+  bool m_finished{false};
+};
+}  // namespace frc2