Make certain gptq options customizable via model specific mapping

[shaahji]

Make certain gptq options customizable via model specific mapping

This is to avoid hardcoding these paramters in config files for models that aren't (like phi3) yet officially supported by auto-gptq.

Checklist before requesting a review

• Add unit tests for this change.
• Make sure all tests can pass.
• Update documents if necessary.
• [ x Lint and apply fixes to your code by running lintrunner -a
• Is this a user-facing change? If yes, give a description of this change to be included in the release notes.
• Is this PR including examples changes? If yes, please remember to update example documentation in a follow-up PR.

(Optional) Issue link

[jambayk]

Thanks!