feat: Add megatron to hf converter

[ashors1]

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[terrykong]

nice addition!

i have a feeling these converters will be quite brittle. do you think we can do some kind of functional test that helps us validate this diamond:

graph LR
  HF1[HF qwen] --> MCORE[mcore qwen]
  MCORE --> HF2[HF qwen]
  HF1 --> DCP[DCP qwen]
  DCP --> HF2

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[terrykong]

can you add a comment in the nemo submodule why you set the PP=1 in the submodule's commit? it'll help us when we need to port the changes over to nemo.tron's replacement?

[ashors1]

can you add a comment in the nemo submodule why you set the PP=1 in the submodule's commit? it'll help us when we need to port the changes over to nemo.tron's replacement?

Yep, done