Add table and database aliases to system.tables and system.databases

Why it matters

This feature simplifies querying system tables by providing commonly used column aliases. It enhances usability and readability of queries accessing metadata about tables and databases.

How to use it

Users can now query the system.tables and system.databases system tables using the new table and database aliases respectively, for example:

SELECT table,  FROM system.tables WHERE database = 'default';

and

SELECT database,  FROM system.databases;