ARROW-10800 [Rust] [Parquet] Provide access to the elements of parquet::record::{List, Map}
ARROW-10800 [Rust] [Parquet] Provide access to the elements of parquet::record::{List, Map}

Adds public functions for both List and Map that provide access to their internal vecs via a slice

Closes #8827 from seen/ARROW-10800-expose-elements

Authored-by: Sean Moran <75b68bea6231d591f725f938eb3709c9e82d05c7@gmail.com>
Signed-off-by: Neville Dipale <4e1ab218b24f06847d563ff3773c7517c139f863@gmail.com>

apache/arrow,apache/arrow,cpcloud/arrow,apache/arrow,kou/arrow,wesm/arrow,wesm/arrow,apache/arrow,cpcloud/arrow,apache/arrow,laurentgo/arrow,icexelloss/arrow,cpcloud/arrow,laurentgo/arrow,cpcloud/arrow,cpcloud/arrow,laurentgo/arrow,kou/arrow,icexelloss/arrow,laurentgo/arrow,wesm/arrow,kou/arrow,kou/arrow,icexelloss/arrow,wesm/arrow,icexelloss/arrow,kou/arrow,apache/arrow,icexelloss/arrow,apache/arrow,cpcloud/arrow,cpcloud/arrow,kou/arrow,apache/arrow,wesm/arrow,wesm/arrow,wesm/arrow,wesm/arrow,wesm/arrow,cpcloud/arrow,wesm/arrow,laurentgo/arrow,laurentgo/arrow,icexelloss/arrow,laurentgo/arrow,apache/arrow,cpcloud/arrow,kou/arrow,laurentgo/arrow,kou/arrow,wesm/arrow,laurentgo/arrow,icexelloss/arrow,icexelloss/arrow,kou/arrow,icexelloss/arrow,wesm/arrow,kou/arrow,apache/arrow,icexelloss/arrow,cpcloud/arrow,wesm/arrow,laurentgo/arrow,icexelloss/arrow,laurentgo/arrow,laurentgo/arrow,kou/arrow,kou/arrow,kou/arrow,apache/arrow,laurentgo/arrow,cpcloud/arrow,apache/arrow,apache/arrow,cpcloud/arrow,kou/arrow,cpcloud/arrow,icexelloss/arrow,cpcloud/arrow,laurentgo/arrow,laurentgo/arrow,icexelloss/arrow,icexelloss/arrow,wesm/arrow,apache/arrow