Allow writing to GCS paths

[bnaul]

This is quite a bit simpler than #8508 since gcsfs allows for writing text-type blobs so I think it makes sense to track separately.

See #8508 (comment) for additional context.

[yu-iskw]

@bnaul Thank you for the awesome work. Does it support only CSV format? If so, do we have a plan to generarize the function with the other formats?