[examples] Zero motors on disabledInit() in sim physics examples (#2906)

This ensures that mechanisms will stop moving if the robot is disabled while motors are in motion

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

@@ -31,6 +31,7 @@ void Robot::RobotPeriodic() { frc2::CommandScheduler::GetInstance().Run(); }
  */
 void Robot::DisabledInit() {
   frc2::CommandScheduler::GetInstance().CancelAll();
+  m_container.ZeroAllOutputs();
 }
 
 void Robot::DisabledPeriodic() {}

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

@@ -36,6 +36,8 @@ RobotContainer::RobotContainer() {
       {&m_drive}));
 }
 
+void RobotContainer::ZeroAllOutputs() { m_drive.TankDriveVolts(0_V, 0_V); }
+
 const DriveSubsystem& RobotContainer::GetRobotDrive() const { return m_drive; }
 
 void RobotContainer::ConfigureButtonBindings() {

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

@@ -30,6 +30,7 @@ class RobotContainer {
  public:
   RobotContainer();
 
+  void ZeroAllOutputs();
   frc2::Command* GetAutonomousCommand();
   const DriveSubsystem& GetRobotDrive() const;