Reading Avro files supports other types

### Is your feature request related to a problem or challenge?

I am now integrating [incubator-paimon](https://github.com/apache/incubator-paimon)(it is a streaming data lake platform), when reading the avro file, an exception message will appear: **expected avro schema to be a record**, because `AvroArrowArrayReader` only supports `AvroSchema::Record`, but the avro file format of paimon is Union type（[code here](https://github.com/apache/incubator-paimon/blob/d2ddaa9bfb865a93b12c7a0294cf936071bbc08b/paimon-format/src/main/java/org/apache/paimon/format/avro/AvroSchemaConverter.java#L224)）

### Describe the solution you'd like

It would be better if the parsing format could be implemented by the user. The default implementation is still the current way, no problem.

### Describe alternatives you've considered

My current solution: [here](https://github.com/Asura7969/arrow-datafusion/blob/8e3b23561baded77c1604a936dea1f40d30ebd66/datafusion/core/src/datasource/avro_to_arrow/arrow_array_reader.rs#L84) and [this](https://github.com/Asura7969/arrow-datafusion/blob/8e3b23561baded77c1604a936dea1f40d30ebd66/datafusion/core/src/datasource/avro_to_arrow/arrow_array_reader.rs#L110)

### Additional context

_No response_

Start with AvroArrowArrayReader and the linked arrow_array_reader.rs examples to understand the current Record-only path and the proposed user-provided parsing approach. Define an extension point that preserves the current default while allowing Union Avro input such as Paimon’s, then verify both the existing reader behavior and the new path.

Written by the indexing model from the issue text.