* Create minimalistic plugin map and test plugin.
* Pass secrets and attributes to the plugin when creating catalogs or sets. Add tests for CreateSet and CreateCatalog repo methods.
* make fmt and extract out getPrivateCatalog and getCatalog helper methods.
* Exporting TestPluginServer so it can be used in the handlers.
* Keep separate persisted data from host catalogs lookups which facilitate passing it onto the plugins.
* Add TODO to merge get Catalog and get Persisted data.
* Adding tests for unimplemented being returned by the plugin.
* Use GetFields() instead of AsMap() to confirm attributes should be populated. Make clone consistent between catalog and sets.
Co-authored-by: Jeff Mitchell <jeffrey.mitchell@gmail.com>