Intl Format Cache

A memoizer factory for Intl format constructors (Intl.NumberFormat, Intl.DateTimeFormat, IntlMessageFormat, IntlRelativeFormat). Current version 4.3.1, part of the FormatJS suite. Creates cache keys via JSON.stringify of arguments, including ordered options keys. Benchmark shows competitive performance vs fast-memoize, especially on get operations. Intended to be used internally by FormatJS packages; direct use may be redundant if using @formatjs/intl. Ships TypeScript declarations. Stable but low churn.