Add SQLite Engine and Table Function to ClickHouse

Why it matters

This feature enables ClickHouse users to directly query and interact with SQLite databases and tables without needing to export or convert data. It simplifies integration workflows and allows seamless hybrid querying capabilities between ClickHouse and SQLite data.

How to use it

Users can create tables that use the SQLite table engine to query SQLite files or use the SQLite table function within queries to access SQLite data on-the-fly. Additionally, the SQLite database engine allows attaching an entire SQLite database for convenient access. Examples:

CREATE TABLE sqlite_table ENGINE = SQLite('/path/to/sqlite.db', 'table_name');

SELECT * FROM sqlite('/path/to/sqlite.db', 'table_name');

ATTACH DATABASE 'sqlite' ENGINE = SQLite('/path/to/sqlite.db');