Update header_rewrite to use Regex (#12573)

[cmcfarlen]

This cherry-picks #12573 in order to fix #12769

• Update header_rewrite to use Regex

• PR review

• cast to int

• also move dbg for failed regex compile.

(cherry picked from commit a15669b)

[Copilot]

Pull request overview

This PR modernizes the header_rewrite plugin by replacing direct PCRE API usage with the new tsutil Regex wrapper class. This is a cherry-pick from commit #12573 to fix issue #12769.

Changes:

• Replaced PCRE-specific data structures (ovector, pcre pointers) with the new Regex and RegexMatches classes
• Updated regex compilation and matching to use the Regex API
• Removed direct PCRE library dependency from CMakeLists.txt

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
plugins/header_rewrite/resources.h	Replaced ovector-related members with RegexMatches object
plugins/header_rewrite/resources.cc	Removed ovector initialization code
plugins/header_rewrite/regex_helper.h	Updated to use Regex class instead of pcre pointers
plugins/header_rewrite/regex_helper.cc	Implemented regex operations using new Regex API
plugins/header_rewrite/matcher.h	Updated regex matching to use RegexMatches
plugins/header_rewrite/conditions.cc	Simplified capture group access using RegexMatches indexing
plugins/header_rewrite/CMakeLists.txt	Removed PCRE library dependency

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[Copilot]

Comparing int32_t (size()) with int (_ix) can lead to signed comparison warnings. Since _ix is validated to be >= 0 in set_qualifier, consider casting _ix to size_t or int32_t for the comparison to avoid potential warnings.

Suggested change

	if (res.matches.size() > _ix) {
	s.append(res.matches[_ix]);
	if (res.matches.size() > static_cast<size_t>(_ix)) {
	s.append(res.matches[static_cast<size_t>(_ix)]);