* extra data source read methods
* update tests
* more tests
* fix more tests; actually initialize retriever instead of sending nil
* moving GetAllDataSources isn't strictly required, so keep to minimal changes
* better name for retriever logger
Co-authored-by: Dafydd <72009875+dafydd-t@users.noreply.github.com>
* add compile-time check for DS retriever impl
---------
Co-authored-by: Dafydd <72009875+dafydd-t@users.noreply.github.com>
Co-authored-by: Stephanie Hingtgen <stephanie.hingtgen@grafana.com>