[Community] add `ipex-llm` integration (#12322)

docs/docs/examples/llm/ipex_llm.ipynb

...ex-integrations/llms/llama-index-llms-ipex-llm/.gitignore

...a-index-integrations/llms/llama-index-llms-ipex-llm/BUILD

...ndex-integrations/llms/llama-index-llms-ipex-llm/Makefile

...dex-integrations/llms/llama-index-llms-ipex-llm/README.md

...llama-index-llms-ipex-llm/llama_index/llms/ipex_llm/BUILD

...index-llms-ipex-llm/llama_index/llms/ipex_llm/__init__.py

...ama-index-llms-ipex-llm/llama_index/llms/ipex_llm/base.py

...ntegrations/llms/llama-index-llms-ipex-llm/pyproject.toml

...x-integrations/llms/llama-index-llms-ipex-llm/tests/BUILD

...grations/llms/llama-index-llms-ipex-llm/tests/__init__.py

...lms/llama-index-llms-ipex-llm/tests/test_llms_ipex_llm.py