No method for getting file_resource

In order to get `file_resource`, you need to make the HTTP request manually e.g.

```python
req = client.call_api('GET', file.file_resource,
header_params={'Authorization': config.get_basic_auth_token()})
req.read()
data = client.response_deserialize(
response_data=req,
response_types_map={'200': 'bytes'}
).data

assert type(data) is bytes
```

Start by tracing the Python client's existing methods and the client.call_api and response_deserialize entry points used in the example. Identify how file_resource is represented and verify that the new method handles the response as bytes; done means callers no longer need to make the HTTP request manually.

Written by the indexing model from the issue text.