Add Trigger factories for common robot state events

[Oblarg]

These would sugar event bindings for transitions between the various robot control modes, etc:

// naming and location TBD
static Trigger disabled() {
  return new Trigger(DriverStation::isDisabled);
}

The static factory methods doing this could live on Trigger, or on the classes whose state they're relevant to.

[a-viv-a]

This would certainly be nice, it can already be achieved by modifying the Robot.java file and calling new methods in your RobotContainer (is there a better way at present?). I figured there was some reason these events weren't exposed.

[Starlight220]

it can already be achieved by modifying the Robot.java file and calling new methods in your RobotContainer (is there a better way at present?)

It could be achieved like the implementation in the original post: new Trigger(DriverStation::isAutonomous) etc.

If you're calling Robot from your RobotContainer, that's a circular dependency code smell.

[Oblarg]

@isaec these aren't exposed mostly because the current command-based API is still evolving and no one had thought to add them yet.

[Oblarg]

@isaec along these lines, if you can think of other convenience factories that'd be useful, please open github issues for them.