[Storage File] preserve content type header

[gracewilcox]

Adding decorator to keep Content-Type headers for specific operation in Go to preserve back compatibility

[github-actions]

Next Steps to Merge

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• ❌ This PR targets either the main branch of the public specs repo or the RPSaaSMaster branch of the private specs repo. These branches are not intended for iterative development. Therefore, you must acknowledge you understand that after this PR is merged, the APIs are considered shipped to Azure customers. Any further attempts at in-place modifications to the APIs will be subject to Azure's versioning and breaking change policies. Additionally, for control plane APIs, you must acknowledge that you are following all the best practices documented by ARM at aka.ms/armapibestpractices. If you do intend to release the APIs to your customers by merging this PR, add the PublishToCustomers label to your PR in acknowledgement of the above. Otherwise, retarget this PR onto a feature branch, i.e. with prefix release- (see aka.ms/azsdk/api-versions#release--branches).
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Comment generated by summarize-checks workflow run.

[github-actions]

API Change Check

APIView identified API level changes in this PR and created the following API reviews

Language	API Review for Package
TypeSpec	Storage.File
Python	azure-storage-file-share
JavaScript	@azure/storage-file-share

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Comment generated by After APIView workflow run.

[catalinaperalta]

probably need a suppression over each decorator

[catalinaperalta]

need to get tsp validation passing before this can get merged in, look at the check for info