RexExp's d flag is not recognized by QjSEngine

The documentation refers to ECMA-262 in the description of QJSEngine::QJSEngine (https://doc.qt.io/qt-6/qjsengine.html#QJSEngine-1) and it can be read above "QJSEngine provides a compliant ECMAScript implementation".

Unfortunately, `RegExp.prototype.hasIndices` and `d` flag support are missing (https://262.ecma-international.org/13.0/#sec-get-regexp.prototype.hasIndices / https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp/hasIndices).