Distributed Training Template

[kohankhaki]

• This pull request introduces a new distributed finetuning template for LLMs, enabling scalable training using either DDP or FSDP with Hydra and Submitit orchestration. It adds a complete configuration, launch, and training pipeline, along with documentation and a compute config for multi-GPU training.
• Added a Slurm compute configuration (bon_echo/a40_4x.yaml) for running jobs on 4xA40 GPU nodes, including resource and partition settings.