Improve Regex Group Recognition and Refine regexp_tree Dictionary

Why it matters

This feature refines how ClickHouse processes and interprets groups within regular expressions, resulting in more accurate parsing and better utility of the regexp_tree dictionary. It improves users' ability to extract and analyze structured data from strings using regular expressions.

How to use it

Users benefit from the enhanced group recognition automatically when working with regular expressions and the regexp_tree dictionary. No additional configuration is required; simply use the regexp_tree dictionary and regular expressions as usual to take advantage of the improved parsing.