Added buildAutoChooser to C++ lib

[ThePhoenixFox]

Added a equivalent version of buildAutoChooser for cpp from java.
Using the std::filesystem, we can inspect the files on the drive.
Since SendableChooser doesn't allow for rvalue storage, we need to store the commands ourselves so the user will not get a nullptr when trying to access a command* from GetSelected().

[mjansen4857]

I'd recommend running builds locally to help find any issues a bit easier.

./gradlew build

You can also fix formatting issues with ./gradlew spotlessApply

[ThePhoenixFox]

Sorry, this is my first time doing this. When I tried to run gradlew on my device, I got errors saying that the settings couldn't be found.

[mjansen4857]

No worries.

I usually have pretty good luck with IntelliJ so you might want to give that a try. It has built in gradle support that usually takes care of setting up everything without any issues.

WPILib VSCode also works. The "Build robot code" option should do the same thing. Does that work for you? You have to also make sure you have the pathplannerlib folder open and not the root pathplanner repo folder or it won't work.

[ThePhoenixFox]

There are two versions of getAutonomousCommand() in the Writerside wiki. The first one is the easy readable one while the second one creates a frc2::CommandPtr since that is what most example programs use for their default return type.

pathplanner/Writerside/topics/pplib-Build-an-Auto.md

Lines 506 to 514 in da4d22c

	frc2::Command* RobotContainer::getAutonomousCommand() {
	// Returns a frc2::Command* that is freed at program termination
	return autoChooser.GetSelected();
	}
	frc2::CommandPtr RobotContainer::getAutonomousCommand() {
	// Returns a copy that is freed after reference is lost
	return frc2::CommandPtr(std::make_unique<frc2::Command>(*autoChooser.GetSelected()));
	}