[WIP] support mcore_bridge

[Jintao-Huang]

Features:

1. During training, weights can be loaded directly from safetensors format and saved as safetensors weights. This eliminates the model conversion step.
2. Multi-node weight conversion support, enabling adaptation for extremely large models.
3. GRPO support: streaming generation of safetensors format state_dict from megatron model.
4. LoRA weight export

[gemini-code-assist]

Note

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[arvyanh]

Is there a plan for when this will be implemented? Facing some disk space and efficiency issue doing the 235B and 671B models lately
I could try to implement it if not doing that right now?