Allow Trailing Commas in Multi-item Types

Why it matters

This feature improves query syntax flexibility by permitting a trailing comma after the last item in type declarations. It helps prevent syntax errors caused by accidental trailing commas and aligns ClickHouse's syntax with common programming language practices, enhancing user convenience and reducing errors.

How to use it

Users can simply add a trailing comma after the last item in multi-element type definitions without causing a syntax error. No special enabling is required; this behavior is supported automatically after the update.