[GR-57588] Implement Regular Expression Pattern Modifiers

[fniephaus]

TL;DR

We plan to implement Regular Expression Pattern Modifiers in GraalJS.

Details

Adds support for inline RegExp pattern modifiers. Modifiers allow you to change the currently active RegExp flags within a subexpression. (?imsx-imsx:subexpression) — Sets or unsets (using -) the specified RegExp flags for the subexpression.

Example:

const re2 = /^(?i:[a-z])[a-z]$/;
re2.test("ab"); // true
re2.test("Ab"); // true
re2.test("aB"); // false