[azureml model catalog]MLflow-transformer model path

[trajepl]

Describe your changes

For transformers model like phi2/phi3 in aml model cataklog, it is hosted with mlflow model format.
But Genai require the input model format is standard transformers structure.

This pr is used to fill this gap to let model builder can convert aml mlflow-transformers models.

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]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[jambayk]

Please push an empty commit or rebase from main to rerun the lint check which has already been fixed in main.