Add SamudrACE CM4 piControl baseline configs

[jpdunc23]

Adds scripts and configs for baseline training of SamudrACE on the CM4 piControl dataset.

[oliverwm1]

Took a brief look—I think it generally looks good and appreciate the readme. A couple thoughts:

• how do these scripts related to the existing cm4-ocean, cm4-atmosphere and cm4/coupled-inference-no-target directories in ace/configs/baselines? It is important to avoid duplication and have a single source of truth for configs, so I suspect that maybe all of those directories should be deleted in favor of this new one?
• why the nested coupled folder? Could just have configs/baselines/cm4-piControl right?