Add Solar chat model (#11710)

docs/examples/llm/solar.ipynb

docs/module_guides/models/llms/modules.md

...index-integrations/llms/llama-index-llms-solar/.gitignore

llama-index-integrations/llms/llama-index-llms-solar/BUILD

...a-index-integrations/llms/llama-index-llms-solar/Makefile

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

.../llms/llama-index-llms-solar/llama_index/llms/solar/BUILD

...llama-index-llms-solar/llama_index/llms/solar/__init__.py

...lms/llama-index-llms-solar/llama_index/llms/solar/base.py

...x-integrations/llms/llama-index-llms-solar/pyproject.toml