Intent to ship: Duplicate Named Capturing Groups

[Daniel Minor]

As of Firefox 129 I intend to turn Duplicate Named Capturing Groups for regular expressions on by default. They have been developed behind the preference `javascript.options.experimental.regexp_duplicate_named_groups`. The proposal advanced to Stage 4 of the TC39 process during the April 2024 plenary and has already been shipped in JavaScriptCore and V8.

Bug to turn on by default: https://bugzilla.mozilla.org/show_bug.cgi?id=1903288

Standard: https://github.com/tc39/proposal-duplicate-named-capturing-groups