regular_expression: Improve ES2025 proposal-duplicate-named-capturing-groups logic

[leaysgur]

Done in #6847 , but there is room for performance improvement.

We want to keep the code as simple as possible and process the current 2 loops in 1 loop for duplicates detection.

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https://github.com/tc39/proposal-duplicate-named-capturing-groups https://tc39.es/ecma262/#sec-mightbothparticipate

For now, /(?<a>.)(?<a>.)/ is invalid syntax, name a is duplicated.

With this change, we can use the same name if they are splitted by | and in the same Disjunction like /(?<a>.)|(?<a>.)/.

But it still not allowed in some cases like /(?<n>|(?<n>))/, /(?<n>(?<n>)|)/, /((?<n>)|(?<n>))(?<n>)/, etc...

You need to track nesting level and | to mange scope.

TODOs

• [ ] Update count capturing parens logic to allow duplicates in certain cases
  • https://github.com/oxc-project/oxc/blob/1282221e36a7b5be53ba81278507218abc90ed79/crates/oxc_regular_expression/src/parser/pattern_parser/state.rs#L60
  • No need to change parser main logic
• [x] Update README
  • https://github.com/oxc-project/oxc/blob/aa7718ab7bf0544b21564658a919307022f8824a/crates/oxc_regular_expression/README.md
• [x] Update local tests
  • https://github.com/oxc-project/oxc/blob/aa7718ab7bf0544b21564658a919307022f8824a/crates/oxc_regular_expression/src/body_parser/mod.rs
• [x] Enable conformance tests
  • https://github.com/oxc-project/oxc/blob/aa7718ab7bf0544b21564658a919307022f8824a/tasks/coverage/src/test262/mod.rs#L103-L104

[preyneyv]

I'd like to take a stab at this!

[Boshen]

@preyneyv You may continue with https://github.com/oxc-project/oxc/pull/6847