Add an option to allow auto conversion from empty fields to NULL

Right now, Parquet Writer throws out an exception:

`Parquet record is malformed: empty fields are illegal, the field should be ommited completely instead`

when an empty field (array or struct or map I guess?) is written.

The suggestion here is to add an option "auto_convert_empty_fields_to_null" that convert empty fields to null automatically on write.

The LOC to change is [here:](https://sourcegraph.com/github.com/apache/parquet-mr/-/blob/parquet-column/src/main/java/org/apache/parquet/io/MessageColumnIO.java#L328)
> `if (emptyField) {`
> ` {{   throw new ParquetEncodingException("empty fields are illegal, the field should be ommited completely instead");`}}
> ``}
 

**Reporter**: [Zheng Shao](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=zshao)

_{**Note**: *This issue was originally created as [PARQUET-1945](https://issues.apache.org/jira/browse/PARQUET-1945). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*}

Inizia in parquet-column/src/main/java/org/apache/parquet/io/MessageColumnIO.java, intorno al blocco `if (emptyField)` alla riga 328, quindi traccia il percorso con cui le opzioni di Parquet Writer raggiungono questo codice. Definisci dove deve trovarsi l’opzione `auto_convert_empty_fields_to_null` e verifica che gli array, gli struct o le map vuoti vengano scritti come null invece di generare l’eccezione per record malformato; l’issue non indica alcun file di test.

Scritto dal modello di indicizzazione a partire dal testo della issue.