add model_reference_arn in signature

[suzhoum]

Issue #, if available:
Addressed two issues:

1. Not compatible with latest sagemaker #130
2. Only create policy when not already existed due to restrictions on "Permission Mutation Policies" and we will lose policy that allows us to create new roles.

Description of changes:

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[tonyhoo]

Thanks for the quick fix!

[prateekdesai04]

Should this change also propagate to the AutoGluonSagemakerInferenceModel class followed by wherever deploy is called in cloud_predictor.py and sagemaker_backend.py ?

[suzhoum]

This might not be necessary. My take is that we need to align all args under the function prepare_container_def with the sagemaker definition here https://sagemaker.readthedocs.io/en/stable/api/inference/model.html#sagemaker.model.Model.prepare_container_def, but we are not really using any of them inside the function.

[github-actions]

Job PR-131-2fb8489 is done.
Docs are uploaded to https://d12sc05jpx1wj5.cloudfront.net/PR-131/2fb8489/index.html

[github-actions]

Job PR-131-43c2a6c is done.
Docs are uploaded to https://d12sc05jpx1wj5.cloudfront.net/PR-131/43c2a6c/index.html