add nvidia nim llm support (#13176)

docs/docs/examples/llm/nvidia.ipynb

...ndex-integrations/llms/llama-index-llms-nvidia/.gitignore

llama-index-integrations/llms/llama-index-llms-nvidia/BUILD

...-index-integrations/llms/llama-index-llms-nvidia/Makefile

...index-integrations/llms/llama-index-llms-nvidia/README.md

...lms/llama-index-llms-nvidia/llama_index/llms/nvidia/BUILD

...ama-index-llms-nvidia/llama_index/llms/nvidia/__init__.py

...s/llama-index-llms-nvidia/llama_index/llms/nvidia/base.py

.../llama-index-llms-nvidia/llama_index/llms/nvidia/utils.py

...-integrations/llms/llama-index-llms-nvidia/pyproject.toml

...dex-integrations/llms/llama-index-llms-nvidia/tests/BUILD

...tegrations/llms/llama-index-llms-nvidia/tests/conftest.py

...s/llama-index-llms-nvidia/tests/test_additional_kwargs.py

...ations/llms/llama-index-llms-nvidia/tests/test_api_key.py

...ms/llama-index-llms-nvidia/tests/test_available_models.py

...ns/llms/llama-index-llms-nvidia/tests/test_integration.py

...ns/llms/llama-index-llms-nvidia/tests/test_mode_switch.py

...rations/llms/llama-index-llms-nvidia/tests/test_nvidia.py

.../llama-index-llms-openai/llama_index/llms/openai/utils.py

...-integrations/llms/llama-index-llms-openai/pyproject.toml