* Return dataframe directly from the backend
* Streamline some transforms
* Fix lint issues
* Remove unused lib
* Fix datasource test
* Fix imports and add some typings
* Fix the typings and some tests
* Add private doc comment
* Remove private tag
* Add comments
* Fix some API docs issues
Converts the core testdata data source to use the SDK contracts and by that
implementing a backend plugin in core Grafana in similar manner as an external one.
Co-authored-by: Will Browne <will.browne@grafana.com>
Co-authored-by: Marcus Efraimsson <marefr@users.noreply.github.com>
Co-authored-by: Ryan McKinley <ryantxu@gmail.com>