[CodeGen] Remove explicit declaration of the OperationStatus enum

[kinelski]

Summary

OperationStatus is an internal enum generated based on the service's response, and we're explicitly declaring it even though we are not renaming any of its auto-generated members. The explicit declaration was originally added to overwrite its access modifier, since CodeGen defaults to public. At some point we started making generated types internal by default, as it can be seen in the autorest.md file.

However, if the explicit declaration of OperationStatus is removed, the generated type is made public.

Goal

Find out what's causing the issue.

• If it's a CodeGen issue, file a bug and update the Form Recognizer client once it's fixed. If it can't get fixed, leave the OperationStatus as it is and close this issue.
• If it's an error on the FormRecognizer's side, fix it.