deepspeed_to_megatron several issues

1. A recent commit removed `tools/convert_checkpoint/deepspeed_checkpoint.py` but there is still an attempt to import it in `tools/convert_checkpoint/deepspeed_to_megatron.py`. The other scripts in the folder appear to be ok. I guess the import on the line 7 should be changed from `from .deepspeed_checkpoint import ARGS_KEY, DeepSpeedCheckpoint` to `from deepspeed.checkpoint.deepspeed_checkpoint import ARGS_KEY, DeepSpeedCheckpoint`?

2. https://github.com/microsoft/Megatron-DeepSpeed/issues/91 applies here as well.

3. The function `_renest_sd` defined on line 90, splits the keys, but I encounter a `ValueError: too many values to unpack (expected 2)` as one of the keys is named `word_embeddings.norm.weight`, containing two dots. There are probably more such layer names. I'm attempting to convert my own model bf16_zero (pp=1, tp=1) checkpoints to megatron and/or hf format. Entirely possible this is all my own wrongdoing. If so, please advise, how to successfully convert.