Add proper support for string starts/ends operators

The current implementation for String `starts` and `ends` operators is a switch fall through to `contains`. Proper SQL implementations with `LIKE %` and `LIKE %` should be provided instead.

Locate the Java implementation of the String `starts` and `ends` operators, beginning with the switch that currently falls through to `contains`. Verify the generated SQL uses `LIKE %` for `starts` and `LIKE %` for `ends`, and add or update the relevant operator tests if they exist.

Rédigé par le modèle d'indexation à partir du texte de l'issue.