Make DatasetInfo work without Datastore module enabled

[dafeder]

In the context of #3746, we want to make common not depend on datastore. One place it does heavily is in the DatasetInfo class. Let's make sure this service can work if datastore is not enabled, and simply return less info.

In the future, we should either set up some kind of plugin or subscriber system so that any module can add info to the core dataset info object. OR (even better) we should maybe find a way to stop using this class altogether. It is kind of an anti-pattern.