Fix patching of NeMo tokenizers for correct Lambada evaluation
<!-- pylint-output-strict-mode-false -->

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---

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

```
************* Module nemo.export.trt_llm.nemo_ckpt_loader.nemo_file
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:43:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:72:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:79:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:95:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:103:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:113:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:119:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:124:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:135:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:166:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:173:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:187:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:191:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:200:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:225:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:236:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:257:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:305:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:349:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:434:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:438:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:449:0: C0115: Missing class docstring (missing-class-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:461:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:501:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:538:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:551:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:27:0: W0611: Unused import tensorstore (unused-import)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:37:0: W0611: Unused SentencePieceTokenizer imported from nemo.export.sentencepiece_tokenizer (unused-import)

-----------------------------------
Your code has been rated at 9.23/10
```

---

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/11918628721) 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 ?

The output of patched `batch_decode` method differs from the desired output used so far (dropped one level of nesting). This resulted in empty `model_output` after [postprocessing in Lambada accuracy check](https://github.com/NVIDIA/NeMo/blob/425a4dd0f31ca10b83ad42bb540e8007f2f9bf1b/tests/export/nemo_export.py#L134) and yields incorrect [100% relaxed accuracy](https://github.com/NVIDIA/NeMo/blob/425a4dd0f31ca10b83ad42bb540e8007f2f9bf1b/tests/export/nemo_export.py#L143) score.

**Collection**: NLP / LLM

# Changelog 

Patching for NeMo tokenizer:
- For HuggingFace: unwrap the original methods
- For SentencePiece: define (quasi) equivalent methods based on https://github.com/NVIDIA/NeMo/blob/main/nemo/export/sentencepiece_tokenizer.py

# 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
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