Add a new yaml configuration to [oellm-autoexp](https://github.com/OpenEuroLLM/oellm-autoexp/tree/refactor/config/experiments) that follows implements the [MoE configuration](https://github.com/OpenEuroLLM/oellm_pretrain/blob/dev_lumi/config/qwen3_like_A400M_2B.yaml) that we want to use as a reference.