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/PrintCommand.cpp

@@ -0,0 +1,16 @@
+/*----------------------------------------------------------------------------*/
+/* 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/PrintCommand.h"
+
+using namespace frc2;
+
+PrintCommand::PrintCommand(const wpi::Twine& message)
+    : CommandHelper{[str = message.str()] { wpi::outs() << str << "\n"; }, {}} {
+}
+
+bool PrintCommand::RunsWhenDisabled() const { return true; }