[cmd] Command-based Template Restructuring

[AngleSideAngle]

#5902 added static triggers for game/robot state changes. This pr, initially #5898, seeks to refactor all command-based templates and examples to declaratively use those triggers along with command factories. Additionally, it removes the split between RobotContainer and Robot, replacing manually scheduling getAutonomous() with a binding to the autonomous() trigger. Indirectly closes #4871.

Specifically, Robot.java in the default commandbased template looks like this:

import static edu.wpi.first.wpilibj2.command.button.RobotModeTriggers.*;

public class Robot extends CommandRobot {

  private final ExampleSubsystem m_exampleSubsystem = new ExampleSubsystem();

  private final CommandXboxController m_driverController =
      new CommandXboxController(OperatorConstants.kDriverControllerPort);

  public Robot() {
    configureBindings();
  }

  private void configureBindings() {
    autonomous().whileTrue(Autos.exampleAuto(m_exampleSubsystem));

    new Trigger(m_exampleSubsystem::exampleCondition).onTrue(m_exampleSubsystem.exampleCommand());

    m_driverController.b().whileTrue(m_exampleSubsystem.anotherCommand());
  }
}

and the file structure is changed to be:

├── Autos.java
├── Constants.java
├── Main.java
├── Robot.java
└── subsystems
    └── ExampleSubsystem.java

• [ ] Java CommandRobot
• [ ] C++ CommandRobot
• [ ] Java Templates
• [ ] C++ Templates
• [ ] Java Examples
• [ ] C++ Examples

[sciencewhiz]

It seems too close to kickoff to make this kind of change. There's definitely frc-docs changes needed, and RobotBuilder, and there's limited time for beta team feedback.

[AngleSideAngle]

Yeah that's true. I wouldn't mind merging this (and associated docs changes) next year, although I'd like to post it on CD to ask for feedback and thoughts before the season starts.

[Starlight220]

I think it'd be better to keep Autos.java in a commands/ directory; multiple files of commands are very reasonable, and we don't want that cluttering the root package.