Added Support for Custom Query in Multiple Database Sources

Why it matters

This feature allows users to define custom queries when creating dictionary sources from external databases or data storages, enabling more flexible and precise data extraction tailored to specific needs. It solves the limitation of fixed query structures by letting users customize data retrieval logic for dictionary population.

How to use it

Users can specify their own SQL or query string in the dictionary source configuration under the query parameter for supported types such as MySQL, PostgreSQL, ClickHouse, JDBC, and Cassandra. This custom query will be used to fetch data for the dictionary.