Add method to export Schema Avro Schema

**Is your feature request related to a problem or challenge? Please describe what you are trying to do.**
I want to be able to export a schema into the avro format. This would make registering it in other data catalogs much easier. E.g. AWS Glue accepts a Avro Json or json-schema (as a string).

**Describe the solution you'd like**
Add a method that deserializes the struct into the avro schema format (or json schema)

No file, test, or entry point is named. Start by locating the Rust schema representation and any existing serialization APIs, then clarify whether Avro JSON or JSON Schema is required and which mappings are supported. Done means a public export method produces output accepted by the intended catalog, with tests for the agreed mappings.

Written by the indexing model from the issue text.