ClickHouse Dictionary Source: Support Predefined Connections

Why it matters

This feature enables users to leverage predefined connections when configuring ClickHouse dictionaries. It simplifies management of external data sources by reusing existing connection settings, improving maintainability and consistency across dictionary configurations.

How to use it

When defining a dictionary source, users can now specify a predefined connection name instead of full connection parameters. This applies to dictionary source configurations in the dictionary XML files or via CREATE DICTIONARY statements where connection specs are supported.