Support nested column in Spark Parquet vectorized readers

The task is to support nested column type in Spark Parquet vectorized reader. Currently Parquet vectorized reader does not support nested column type (struct, array and map). We implemented nested column vectorized reader for FB-ORC in our internal fork of Spark. We are seeing performance improvement compared to non-vectorized reader when reading nested columns. In addition, this can also help improve the non-nested column performance when reading non-nested and nested columns together in one query.

Parquet: https://github.com/apache/spark/blob/master/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetFileFormat.scala#L173