[small bug + generalization] saving config.yaml to output_dir

[felipemello1]

Currently our WandBLogger has this code:

try:
    output_config_fname = Path(
        os.path.join(
            config.checkpointer.checkpoint_dir,
            "torchtune_config.yaml",
        )
    )
    OmegaConf.save(config, output_config_fname)

    log.info(f"Logging {output_config_fname} to W&B under Files")
    self._wandb.save(
        output_config_fname, base_path=output_config_fname.parent
    )

except Exception as e:
    log.warning(
        f"Error saving {output_config_fname} to W&B.\nError: \n{e}."
        "Don't worry the config will be logged the W&B workspace"
    )

It is great that is saves the config, however, there are a few problems with it:

1. This should be done for every config, not only WandBLogger. One option is to add this to every logger, but maybe this should be elsewhere, so it is not related to the logger.
2. It saves it to the checkpoint_dir, which doesnt make sense. It should save the config to output_dir/...
3. it does try/except, but if it fails to load output_config_fname, the except will also fail, because it tries to print "output_config_fname"

[joecummings]

@felipemello1 Can I assign this to you?

[akashc1]

@felipemello1 @joecummings have a fix for the wandb one here: #2196

I'm happy to add the other changes to that PR too if you'd like, let me know! I definitely need it fixed for the wandb logger :)