CDK-469: Use schema URIs in create command

This updates the create command to pass Schema URIs to DatasetDescriptor, which will set them using the URI option for Hive tables and avoid [CDK-469](https://issues.cloudera.org/browse/CDK-469) for schemas longer than 4k.
I think this should avoid the `fs.exists` check and allow the `FileNotFoundException` from `fs.open` to propagate rather than throwing `IllegalArgumentException`