Restore PTQ tests for Llama2
Closing: tests were added in https://github.com/NVIDIA/NeMo/pull/9064
# What does this PR do ?

Restoring PTQ tests for Llama2 model. The tests are moved here from recently disabled [Jenkinsfile](https://github.com/NVIDIA/NeMo/blob/main/Jenkinsfile).

Testing all methods: FP8, INT8 SQ, INT4 AWQ and special case of NULL (just weights export step).

**Collection**: NLP

# Changelog 
- Setting up data and models
- Testing PTQ script (four variants)

# Usage

If you want to reproduce tests locally, scripts included in `tests.setup` module along with `convert_llama_hf_to_nemo.py ` can be used to create tiny test model and data with the following steps (set `TEST_DATA` variable accordingly):

```python
python tests/setup/data/create_sample_jsonl.py \
  --output_file ${TEST_DATA}/test_quantization/test.json

python tests/setup/models/create_hf_model.py \
  --model_name_or_path meta-llama/Llama-2-7b \
  --output_dir ${TEST_DATA}/llama-ci-hf-tiny \
  --config_updates '{"hidden_size": 256, "num_attention_heads": 4, "num_hidden_layers": 2, "num_key_value_heads": 4}'

python scripts/checkpoint_converters/convert_llama_hf_to_nemo.py \
  --input_name_or_path ${TEST_DATA}/llama-ci-hf-tiny \
  --output_path ${TEST_DATA}/llama_ci.nemo
```

# Jenkins CI

The Jenkins CI system has been replaced by GitHub Actions self-hosted runners.

There's no need to comment `jenkins` on the PR to trigger Jenkins CI.
The GitHub Actions CI will run automatically when the PR is opened.
To run CI on an untrusted fork, a NeMo user with write access must click "Approve and run".

# Before your PR is "Ready for review"
**Pre checks**:
- [x] Make sure you read and followed [Contributor guidelines](https://github.com/NVIDIA/NeMo/blob/main/CONTRIBUTING.md)
- [x] Did you write any new necessary tests?
- [x] Did you add or update any necessary documentation?
- [ ] Does the PR affect components that are optional to install? (Ex: Numba, Pynini, Apex etc)
  - [ ] Reviewer: Does the PR have correct import guards for all optional libraries?
  
**PR Type**:
- [ ] New Feature
- [x] Bugfix
- [ ] Documentation

If you haven't finished some of the above items you can still open "Draft" PR.


## Who can review?

Anyone in the community is free to review the PR once the checks have passed. 
[Contributor guidelines](https://github.com/NVIDIA/NeMo/blob/main/CONTRIBUTING.md) contains specific people who can review PRs to various areas.
