Mypy error: Function has duplicate type signatures

[damiondoesthings]

• Package Name: azure-storage-file-share
• Package Version: 12.6.0
• Operating System: Mac OS 11.6 / ubuntu-18.04
• Python Version: 3.8

Describe the bug
Duplicate type information causes type checker to fail.
mypy 0.910 will fail with output azure/storage/fileshare/_file_client.py:684: error: Function has duplicate type signatures

To Reproduce
Steps to reproduce the behavior:

1. call the download_file() function on a FileClient in a python file
2. create mypy.ini with [mypy-azure.storage.fileshare.*]] ignore_missing_imports = True
3. run mypy on the python file

Expected behavior
Mypy should find no errors in the Azure fileshare package.

Additional context
This is caused by types in the download_file function being specified twice:

    def download_file(
            self, offset=None,  # type: Optional[int]
            length=None,  # type: Optional[int]
            **kwargs
        ):
        # type: (Optional[int], Optional[int], Any) -> StorageStreamDownloader```

[damiondoesthings]

Already fixed with This pull request