Expose 'upload' class from 'upload_from_file()' #1077
Description
When uploading a large file with the Blob.upload_from_file() method it would be extremely convenient to be able to access properties of the upload class that is generated in this method to view upload progress, as well as assert the other properties of that wrapped class.
Something as simple as this:
def upload_from_file(self, file_obj, rewind=False, size=None,
content_type=None, num_retries=6, client=None):
...
self.upload = transfer.Upload(file_obj, content_type, total_bytes,
auto_transfer=False,
chunksize=self.chunk_size)