feat: Add Xorbits Inference for local deployment

[Bojun-Feng]

Description

This PR adds Xorbits Inference (Xinference for short) as a custom LLM, together with proper tests and usage examples. Xorbits Inference is a distributed deployment framework so users can scale the local deployment of custom models.

See #6845 for a previous discussion regarding the integration of Xorbits Inference.

Here is an excerpt from the discussion with performance data and charts.

Type of Change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• Added new unit/integration tests
• Added new notebook (that tests end-to-end)
• I stared at the code and made sure it makes sense

[Bojun-Feng]

All checks have successfully passed. @logan-markewich please don't hesitate to reach out if you have any questions or concerns. If everything is in order, feel free to merge this PR.

[logan-markewich]

Thanks for the work on this @Bojun-Feng !