Add Mistral fp16 config

[apsonawane]

Describe your changes

Add float16 configuration to Mistral.

Checklist before requesting a review

• Add unit tests for this change.
• Make sure all tests can pass.
• Update documents if necessary.
• 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 for adding this example!

[devang-ml]

Please add e2e example that uses the output model produced using mistral_fp16_optimize.json

Thanks!

[jambayk]

Thanks!