Wizard with async fileHandler in Field.Upload in Iterate.Array

[langz]

Motivation: https://dnb-it.slack.com/archives/CMXABCHEY/p1764686253625159
As that issue is actually using Field.Upload in Iterate.Array in a step of a Wizard.

Here's a scenario where it does not work as expected, when wrapped in an Iterate.Array 🤔

Video (Next button is not disabled and loading after the click, and there's some issues with the Field.Upload's as only the last file uploaded is actually "uploaded" / displayed in the list of files):

Screen.Recording.2025-12-19.at.10.34.03.mov

Here's a CSB of the original issue that we improved, just to demo that the next button is disabled and loading/spinning, etc).
https://codesandbox.io/p/devbox/lively-sun-nr2yft?workspaceId=ws_LbiDwJdEBdbwxH2AkyAyVE

Originally posted by @langz in #6032 (comment)