[New Feature] Support openGauss pg_cataglog.pg_description table empty query

[wbcfwbe]

Background

This task is a subtask of issue #24662.

Hi community.
ShardingSphere is committed to providing a multi-source heterogeneous, enhanced database platform and further building an ecosystem around the upper layer of the platform.
So ShardingSphere needs to be compatible with the inquiries of the system database of various types of databases, such as MySQL, PostgreSQL, and OpenGauss.

So we want to mock all system database tables and views query, return to the empty result.

Tasks

In this issue, we will implement the empty query of the following system tables/views:

• pg_description
• pg_directory
• pg_enum
• pg_extension
• pg_extension_data_source

Refer PR

You can refer to the following similar PR to complete the task.
MySQL: #25076, #25256, PostgreSQL: #25752

[FlyingZC]

The current task has been completed, please refer to the parent task #24662, I will close this issue.