Adds Promise.allSettled(), which returns a promise that is fulfilled with an array of promise state snapshots, but only after all the original promises have settled, in other words after it has either fulfilled or rejected.
https://github.com/tc39/proposal-promise-allSettled#overview-and-motivation
Docs: https://v8.dev/features/promise-combinators#promise.allsettled
Explainers: https://v8.dev/features/promise-combinators#promise.allsettled