[SPARK-14904][SQL] Put removed HiveContext in compatibility module

## What changes were proposed in this pull request?
This is for users who can't upgrade and need to continue to use HiveContext.

## How was this patch tested?
Added some basic tests for sanity check.

This is based on #12672 and closes #12672.

Author: Andrew Or <andrew@databricks.com>
Author: Reynold Xin <rxin@databricks.com>

Closes #12682 from rxin/add-back-hive-context.