Completely remove args from export_llama_lib

[jackzhxng]

Stack from ghstack (oldest at bottom):

• -> Completely remove args from export_llama_lib #11171
• refactor: simplify Llama2Model constructor to take llm_config directly #11170
• refactor: remove backward compatibility and simplify Llama2Model configuration #11169
• refactor: Use LlmConfig for model parameters instead of kwargs #11168
• fix: add missing LlmConfig import and parameter in export_llama_lib.py #11167
• refactor: Replace self.args with LlmConfig in model.py and export_llama_lib.py #11166
• Fix test_llama #11165
• Use llm_config instead of args in export_llama functions #11162
• Convert args to LlmConfig #11081
• Introduce hydra framework with backwards compatibility #11029
• Add new export LLM config #11028

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/11171

• 📄 Preview Python docs built from this PR

Note: Links to docs will display an error until the docs builds have been completed.

This comment was automatically generated by Dr. CI and updates every 15 minutes.

[github-actions]

This PR needs a release notes: label

If your change should be included in the release notes (i.e. would users of this library care about this change?), please use a label starting with release notes:.

If not, please add the release notes: none label.

To add a label, you can comment to pytorchbot, for example
@pytorchbot label "release notes: none"

For more information, see
https://github.com/pytorch/pytorch/wiki/PyTorch-AutoLabel-Bot#why-categorize-for-release-notes-and-how-does-it-work.