Guest Mode should be disabled when the robot is enabled

[jtechau]

When the robot is enabled, especially in teleop but really in any mode, the Guest controller should be disabled. Thus the robot must be explicitly enabled by the driver after enabling the robot.

User Story:

• As a driver, I want the Guest controller to be disabled when the robot is enabled, so that the Guest doesn't have the ability to drive the robot until the Driver explicitly enables it.

[jtechau]

In commit a9293f772f7d5ecda32549f7182763451e518610:

The Robot class is statically referencing RobotContainer. It also has a m_robotContainer object. It might be better to reference the object instance instead of the class.