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/cpp/frc2/command/NotifierCommand.cpp

@@ -0,0 +1,33 @@
+/*----------------------------------------------------------------------------*/
+/* 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 "frc2/command/NotifierCommand.h"
+
+using namespace frc2;
+
+NotifierCommand::NotifierCommand(std::function<void()> toRun,
+                                 units::second_t period,
+                                 std::initializer_list<Subsystem*> requirements)
+    : m_toRun(toRun), m_notifier{std::move(toRun)}, m_period{period} {
+  AddRequirements(requirements);
+}
+
+NotifierCommand::NotifierCommand(NotifierCommand&& other)
+    : CommandHelper(std::move(other)),
+      m_toRun(other.m_toRun),
+      m_notifier(other.m_toRun),
+      m_period(other.m_period) {}
+
+NotifierCommand::NotifierCommand(const NotifierCommand& other)
+    : CommandHelper(other),
+      m_toRun(other.m_toRun),
+      m_notifier(frc::Notifier(other.m_toRun)),
+      m_period(other.m_period) {}
+
+void NotifierCommand::Initialize() { m_notifier.StartPeriodic(m_period); }
+
+void NotifierCommand::End(bool interrupted) { m_notifier.Stop(); }