Feat (brevitas_examples/llm): inference_mode support

[Giuseppe5]

Reason for this PR

Use quant_inference_mode for inference, and expand the classes supported by quant_inference_mode

Changes Made in this PR

Testing Summary

Risk Highlight

• This PR includes code from another work (please detail).
• This PR contains API-breaking changes.
• This PR depends on work in another PR (please provide links/details).
• This PR introduces new dependencies (please detail).
• There are coverage gaps not covered by tests.
• Documentation updates required in subsequent PR.

Checklist

• Code comments added to any hard-to-understand areas, if applicable.
• Changes generate no new warnings.
• Updated any relevant tests, if applicable.
• No conflicts with destination dev branch.
• I reviewed my own code changes.
• Initial CI/CD passing.
• 1+ reviews given, and any review issues addressed and approved.
• Post-review full CI/CD passing.

[nickfraser]

Worth adding this to the SDXL example as well? Otherwise, LGTM!

[Giuseppe5]

We already have this in SDXL IIRC, since we also use torch.compile there, for which quant_inference_mode is required

[Giuseppe5]

Nevermind, I had it in a separate branch. I will merge this and open a new one for SDXL + compile