[parquet_derive] Add inner struct and enum support for writing and reading

**Is your feature request related to a problem or challenge? Please describe what you are trying to do.**

Basically I need to be able to write large vectors of data to/from parquet files. And my record struct type has an enum in it with fields. I would like to be able to do this by just adding `#[derive(ParquetRecordWriter, ParquetRecordReader)]` into my types. This should also support structs within structs, or enums within structs, etc.

It would also be nice if I didn't have to hardcode the number of records to be read. It should be able to know when to stop.

**Additional context**

My development journal can be found [here]() for my problem context.

Start by reading the parquet_derive implementations behind ParquetRecordWriter and ParquetRecordReader. Determine how nested structs and enums, including enums with fields, should map to Parquet data and how reading can detect the end without a hardcoded record count. Done means these derive macros support the requested nested types and automatic stopping behavior.

Written by the indexing model from the issue text.