Add context_logits for eval accuracy calculation in case of multi token prediction tasks
[🤖]: Hi @athitten 👋,

We wanted to let you know that a [CICD pipeline](https://github.com/NVIDIA/NeMo/actions/runs/12684673872) 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 LGTM for `nemo/collections/llm` related changes. > Looks good but can you please run the examples here https://docs.nvidia.com/nemo-framework/user-guide/latest/deployment/llm/optimized/tensorrt_llm.html and make sure nothing is broken?

Hi @oyilmaz-nvidia ran the scripts you pointed with HF llama3-8b converted to nemo2. No errors, everything worked fine. Here's the output

``` Python
python scripts/deploy/nlp/deploy_triton.py --nemo_check
point /workspace/hf_llama3_8b_nemo2_new.nemo --model_type 'llama' --triton_model_name 'llama3-8b' -
-tensor_parallelism_size 1
```
Output of `deploy_triton.py`

``` Python
| cuda_memory_pool_byte_size{1}    | 67108864                                 |
| min_supported_compute_capability | 6.0                                      |
| strict_readiness                 | 1                                        |
| exit_timeout                     | 30                                       |
| cache_enabled                    | 0                                        |
+----------------------------------+------------------------------------------+

I0110 00:42:14.989638 1098739 grpc_server.cc:2558] "Started GRPCInferenceService at 0.0.0.0:8001"
I0110 00:42:14.989788 1098739 http_server.cc:4713] "Started HTTPService at 0.0.0.0:8000"
I0110 00:42:15.030635 1098739 http_server.cc:362] "Started Metrics Service at 0.0.0.0:8002"
E0110 00:42:15.571184 1098739 model_repository_manager.cc:470] "Failed to set config modification time: model_config_content_name_ is empty"
I0110 00:42:15.571553 1098739 model_lifecycle.cc:472] "loading: llama3-8b:1"
I0110 00:42:17.003485 1098739 python_be.cc:2249] "TRITONBACKEND_ModelInstanceInitialize: llama3-8b_0_0 (CPU device 0)"
I0110 00:42:17.484886 1098739 model_lifecycle.cc:839] "successfully loaded 'llama3-8b'"
[01/10/2025-00:42:17] Model serving on Triton is will be started.
```
Inference request:

python scripts/deploy/nlp/query.py -mn 'llama3-8b' -p "Hi, how are you?" -mol 20

Output:
![Screen Shot 2025-01-09 at 4 48 53 PM](https://github.com/user-attachments/assets/cab783fa-024d-4392-aca1-75b2fa35e3fc)

![Screen Shot 2025-01-09 at 4 49 37 PM](https://github.com/user-attachments/assets/02732ecc-5ed6-4648-aaf7-87bf3e108b25)

 <!-- pylint-output-strict-mode-false -->

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

---

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

```
************* Module nemo.collections.llm.api
nemo/collections/llm/api.py:368:0: C0301: Line too long (121/119) (line-too-long)
nemo/collections/llm/api.py:369:0: C0301: Line too long (120/119) (line-too-long)
nemo/collections/llm/api.py:445:0: C0301: Line too long (130/119) (line-too-long)
nemo/collections/llm/api.py:572:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/llm/api.py:15:0: W0611: Unused import os (unused-import)
************* Module nemo.deploy.nlp.query_llm
nemo/deploy/nlp/query_llm.py:29:0: C0115: Missing class docstring (missing-class-docstring)
************* Module nemo.export.trt_llm.tensorrt_llm_run
nemo/export/trt_llm/tensorrt_llm_run.py:506:0: C0301: Line too long (125/119) (line-too-long)
nemo/export/trt_llm/tensorrt_llm_run.py:510:0: C0301: Line too long (136/119) (line-too-long)
nemo/export/trt_llm/tensorrt_llm_run.py:514:0: C0301: Line too long (123/119) (line-too-long)
nemo/export/trt_llm/tensorrt_llm_run.py:557:0: C0301: Line too long (181/119) (line-too-long)
nemo/export/trt_llm/tensorrt_llm_run.py:844:0: C0301: Line too long (153/119) (line-too-long)
nemo/export/trt_llm/tensorrt_llm_run.py:524:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/tensorrt_llm_run.py:533:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/tensorrt_llm_run.py:591:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/tensorrt_llm_run.py:33:0: W0611: Unused Mapping imported from tensorrt_llm.mapping (unused-import)
************* Module nemo.export.vllm_exporter
nemo/export/vllm_exporter.py:38:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/vllm_exporter.py:430:4: C0116: Missing function or method docstring (missing-function-docstring)

-----------------------------------
Your code has been rated at 9.89/10
```

---

Mitigation guide:

* Add sensible and useful docstrings to functions and methods
* For trivial methods like getter/setters, consider adding `# pylint: disable=C0116` inside the function itself
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By applying these rules, we reduce the occurance of this message in future.

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

We wanted to let you know that a [CICD pipeline](https://github.com/NVIDIA/NeMo/actions/runs/12821354408) 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 ?

This PR adds the following changes:

1) Uses `context_logits` to compute `logProbs` in case of eval benchmarks that have multiple token prediction. For ex: `arc_challenge`, `arc_easy`, `winogrande`, `copa` etc., (where as `MMLU`, `lambada` are single token prediction benchmarks. Uses `generation_logits` for these benchmarks to avoid large payload from `context_logits` )

2) In order to get `context_logits` for evals, the PR exposes `gather_context_logits` and `output_context` logits in `export` and `deploy` files similar to previously existed `generation_logits`

3) Introduces `requirements_eval.txt` file to install `lm-eval-harness` in NeMo FW containers. 

**Collection**: [Note which collection this PR will affect]

# Changelog 
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