Clean up llava deps and consolidate all HF deps

[guangy10]

python3 -m examples.portable.scripts.export --model_name="llava" works fine on my mac M1. No strict mode is needed. And can directly working on the most recent transformers lib.

It seems like the old restriction about numpy and transformers are not longer true. If CI gives green light we can cleanup the stale setup for llava and use the root setup (executorch/install_requirements.sh) as the source of truth