Support NeMo MegatronGPTModel

Nobody has claimed this yet.

### 🚀 Feature

Support NeMo's LLM `MegatronGPTModel`

Initial examine:
Found 44 distinct operations, of which 33 (75%) are supported
### Motivation

### Pitch

### Work items

* #340
* #341
* #327
* #342
* #328
* #332
* #329
* #339
* #331
* #338
* #326
* #753

### Running the model

#### Required data

Download the [data tarball](https://drive.google.com/file/d/1MqgWJvTH3F-DkSoyTrzo5MmXuC-yduzp/view?usp=sharing) and extract it into the root of your nemo clone.

#### NeMo installation

To keep the whole thunder team on the same NeMo revisions, and to prevent having a bunch of "modify file to call `thunder.jit()`" instructions, we temporarily maintain our own branch of thunder. You can grab it by cloning `https://github.com/tfogal/NeMo.git`. Make sure you have checked out the `tfogal/thunder-nemo` branch.

To install NeMo, run `python3 -m pip install -e .` from the root of the checked-out directory.

#### Running the network

```
TMPDIR=./foo-mgpt-train
rm -fr ${TMPDIR}; mkdir -p ${TMPDIR}
HYDRA_FULL_ERROR=1 \
THUNDER_ANNOTATE_TRACES=1 \
NEMO_THUNDER_MEGATRON_GPT=1 \
python3 \
examples/nlp/language_modeling/tuning/megatron_gpt_finetuning.py \
trainer.devices=1 \
trainer.num_nodes=1 \
trainer.precision=32 \
trainer.max_steps=4 \
trainer.val_check_interval=4 \
trainer.enable_checkpointing=False \
+trainer.limit_val_batches=2 \
+trainer.limit_test_batches=2 \
exp_manager.checkpoint_callback_params.save_best_model=False \
exp_manager.exp_dir=examples/nlp/language_modeling/gpt_sft_results \
model.peft.peft_scheme=none \
model.optim.name=distributed_fused_adam \
model.restore_from_path=./data/nlp/megatron_gpt/starcoder-ci-nemo/megatron_starcoder_tp1_pp1.nemo \
model.tensor_model_parallel_size=1 \
model.pipeline_model_parallel_size=1 \
model.data.train_ds.file_names=[./data/nlp/megatron_sft/quarel.jsonl] \
model.data.train_ds.num_workers=0 \
model.data.test_ds.file_names=[./data/nlp/megatron_sft/quarel.jsonl] \
model.data.validation_ds.num_workers=0 \
model.data.validation_ds.file_names=[./data/nlp/megatron_sft/quarel.jsonl] \
model.data.test_ds.num_workers=0 \
model.data.train_ds.concat_sampling_probabilities=[1.0]
```

The above command was pulled from NeMo's CI testing for this model and lightly modified to account for other directories and set appropriate environment variables.

cc @tfogal

Start with the listed work items and the NeMo entry point examples/nlp/language_modeling/tuning/megatron_gpt_finetuning.py, then review which of MegatronGPTModel's 44 operations remain unsupported. Use the provided installation and training command to validate progress; done means the model is supported and that run completes as intended.

Written by the indexing model from the issue text.