Added Executable Storage Engine and Table Function for Streaming Data Processing

Why it matters

This feature allows users to integrate external script processing directly within ClickHouse queries, providing a flexible way to handle data transformations or integrations that require custom or external logic, improving extensibility and streamlining workflows.

How to use it

Users can create tables with the Executable storage engine or call the executable table function specifying the external script to run. The data flows through these external scripts in a streaming fashion, enabling real-time processing without intermediate storage.