[examples] Update C++ examples to use CommandPtr (#5988)

Co-authored-by: Tyler Veness <calcmogul@gmail.com>

wpilibcExamples/src/main/cpp/examples/ArmBot/cpp/Robot.cpp

@@ -39,7 +39,7 @@ void Robot::DisabledPeriodic() {}
 void Robot::AutonomousInit() {
   m_autonomousCommand = m_container.GetAutonomousCommand();
 
-  if (m_autonomousCommand != nullptr) {
+  if (m_autonomousCommand) {
     m_autonomousCommand->Schedule();
   }
 }
@@ -51,9 +51,9 @@ void Robot::TeleopInit() {
   // teleop starts running. If you want the autonomous to
   // continue until interrupted by another command, remove
   // this line or comment it out.
-  if (m_autonomousCommand != nullptr) {
+  if (m_autonomousCommand) {
     m_autonomousCommand->Cancel();
-    m_autonomousCommand = nullptr;
+    m_autonomousCommand.reset();
   }
 }
 

wpilibcExamples/src/main/cpp/examples/ArmBot/cpp/RobotContainer.cpp

@@ -60,6 +60,6 @@ void RobotContainer::DisablePIDSubsystems() {
   m_arm.Disable();
 }
 
-frc2::Command* RobotContainer::GetAutonomousCommand() {
-  return nullptr;
+frc2::CommandPtr RobotContainer::GetAutonomousCommand() {
+  return frc2::cmd::None();
 }

wpilibcExamples/src/main/cpp/examples/ArmBot/include/Robot.h

@@ -4,6 +4,8 @@
 
 #pragma once
 
+#include <optional>
+
 #include <frc/TimedRobot.h>
 #include <frc2/command/Command.h>
 
@@ -24,7 +26,7 @@ class Robot : public frc::TimedRobot {
  private:
   // Have it null by default so that if testing teleop it
   // doesn't have undefined behavior and potentially crash.
-  frc2::Command* m_autonomousCommand = nullptr;
+  std::optional<frc2::CommandPtr> m_autonomousCommand;
 
   RobotContainer m_container;
 };

wpilibcExamples/src/main/cpp/examples/ArmBot/include/RobotContainer.h

@@ -5,6 +5,7 @@
 #pragma once
 
 #include <frc2/command/Command.h>
+#include <frc2/command/CommandPtr.h>
 #include <frc2/command/button/CommandXboxController.h>
 
 #include "Constants.h"
@@ -28,7 +29,7 @@ class RobotContainer {
    */
   void DisablePIDSubsystems();
 
-  frc2::Command* GetAutonomousCommand();
+  frc2::CommandPtr GetAutonomousCommand();
 
  private:
   // The driver's controller