Show warning in system.warnings for outdated setting changes

Why it matters

This feature notifies users if they modify any obsolete settings by showing warnings in the system.warnings table. It helps users identify and avoid using outdated configuration options, improving system configuration management and preventing potential issues caused by deprecated settings.

How to use it

Users do not need to enable anything explicitly. If an obsolete setting is changed, a warning will automatically appear in the system.warnings table, which can be queried using a statement like:

SELECT * FROM system.warnings;