ENHANCEMENT: Export resources nested structure as flat columns

For each resource (and we don't know how many a dataset will have) we should be able to parse out each from a nested json into a column per property structure.

Eg. resource.1.name, resource.1.url, resource.2.name, resource.2.url etc

Could be a flag --flat_resources passed in the cli to include this in the export.

Start at the CLI export entry point and trace how nested JSON resources are converted into CSV columns. Confirm how the --flat_resources flag should affect export without changing the default behavior. Done means each resource property is emitted in numbered columns such as resource.1.name and resource.1.url, for any number of resources.

Written by the indexing model from the issue text.