Data masking(null) for column encryption

When user doesn't have permisson on a column that are encrypted by the column encryption feature (parquet-1178), returning a masked value could avoid an exception and let the call succeed.

We would like to introduce the data masking with null values. The idea is when the user gets key access denied and the user can accept null(via a reading option flag), we would return null for the encrypted columns. This solution doesn't need to save extra columns for masked value and doesn't need to translate existing data.

**Reporter**: [Xinli Shang](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=shangx@uber.com) / @shangxinli
**Assignee**: [Xinli Shang](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=shangx@uber.com) / @shangxinli

_{**Note**: *This issue was originally created as [PARQUET-2062](https://issues.apache.org/jira/browse/PARQUET-2062). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*}