Handling tokenizer in PTQ for Nemo 2.0
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beep boop 🤖: 🙏 The following files have warnings. In case you are familiar with these, please try helping us to improve the code base.

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Your code was analyzed with PyLint. The following annotations have been identified:

```
************* Module nemo.collections.llm.quantization.quantizer
nemo/collections/llm/quantization/quantizer.py:240:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/llm/quantization/quantizer.py:273:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/llm/quantization/quantizer.py:316:0: C0116: Missing function or method docstring (missing-function-docstring)
************* Module nemo.export.tensorrt_llm
nemo/export/tensorrt_llm.py:118:0: C0301: Line too long (148/119) (line-too-long)
nemo/export/tensorrt_llm.py:219:0: C0301: Line too long (123/119) (line-too-long)
nemo/export/tensorrt_llm.py:381:0: C0301: Line too long (186/119) (line-too-long)
nemo/export/tensorrt_llm.py:976:0: C0301: Line too long (184/119) (line-too-long)
nemo/export/tensorrt_llm.py:1010:0: C0301: Line too long (131/119) (line-too-long)
nemo/export/tensorrt_llm.py:1014:0: C0301: Line too long (135/119) (line-too-long)
nemo/export/tensorrt_llm.py:1072:0: C0301: Line too long (121/119) (line-too-long)
nemo/export/tensorrt_llm.py:67:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/tensorrt_llm.py:519:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/tensorrt_llm.py:806:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/tensorrt_llm.py:827:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/tensorrt_llm.py:838:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/tensorrt_llm.py:843:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/tensorrt_llm.py:909:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/tensorrt_llm.py:1118:4: C0116: Missing function or method docstring (missing-function-docstring)
************* Module scripts.llm.ptq
scripts/llm/ptq.py:19:0: C0116: Missing function or method docstring (missing-function-docstring)
scripts/llm/ptq.py:70:0: C0116: Missing function or method docstring (missing-function-docstring)

-----------------------------------
Your code has been rated at 9.70/10
```

---

Thank you for improving NeMo's documentation! [🤖]: Hi @janekl 👋,

We wanted to let you know that a [CICD pipeline](https://github.com/NVIDIA/NeMo/actions/runs/11799663314) for this PR just finished successfully

So it might be time to merge this PR or get some approvals

I'm just a bot so I'll leave it you what to do next.

//cc @pablo-garay @ko3n1g
# What does this PR do ?

Save tokenizer in PTQ workflow in order to set it up in `nemo.export` later.

**Collection**: NLP & LLM
# Changelog 
- For [NeMo 2](https://github.com/NVIDIA/NeMo/pull/11237/commits/f3d3501155b2fcd32d05f713198150efe47b6e76): copy full NeMo context in the TensorRT-LLM checkpoint export step 
- For [NeMo 1](https://github.com/NVIDIA/NeMo/pull/11237/commits/c59ab3e89abbdcc4178290ba6e4e350658471477): save HF tokenizer in `huggingface_tokenizer` directory to gradually deprecate "tokenizer_config.yaml" usages
- With these changes [`get_tokenizer`](https://github.com/NVIDIA/NeMo/blob/c6048dcba300fd9fd91d161488e2611de122c37a/nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py#L286-L302) function works for a quantized checkpoint for both Nemo 1 and 2 code paths

# Usage
* You can potentially add a usage example below

```python
# Add a code snippet demonstrating how to use this 
```

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# Additional Information
* Related to # (issue)
