Support `fetch` methods in Criteria API

### Feature description

Criteria API's fetch methods are needed to fetch the association.

No file, test, or entry point is named. Start by locating the Criteria API implementation and its existing association-handling methods, then trace how fetch methods would be exposed and translated. Done means the requested Criteria API fetch methods support fetching associations and are covered by the relevant tests.

Written by the indexing model from the issue text.