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.*}

首先阅读 parquet-1178 中引用的现有列加密功能以及 reader 选项处理逻辑。跟踪密钥访问被拒绝的路径，并确定允许 null 的 flag 应放置在哪里。完成的标准是：只有启用该选项时，加密列才返回 null，同时现有数据无需转换，也无需额外的掩码值列。

由索引模型根据 Issue 内容生成。