Support Reading Array(Record) into Flatten Nested Table in Avro

Why it matters

This feature enables ClickHouse to correctly interpret and flatten nested Array(Record) structures found in Avro data files. It solves the problem of processing complex nested data in Avro by automatically transforming it into a normalized table format, improving usability and compatibility with Avro data pipelines.

How to use it

When reading Avro files that contain nested Array(Record) fields, ClickHouse will now automatically flatten these structures into nested tables during import. Users just need to use the standard FORMAT Avro clause in their INSERT or SELECT queries without additional settings.