Support complex types in Avro nested fields

Why it matters

This feature enables ClickHouse to correctly handle and parse nested complex types (such as arrays, maps, and nested records) within Avro files, improving compatibility and flexibility when ingesting Avro data that includes rich nested structures.

How to use it

Users can now load Avro files containing nested complex types seamlessly using the existing Avro format support in ClickHouse without additional configuration. Simply SELECT or INSERT data as usual from Avro files with nested complex types.