Fix duplicate file upload button for screen reader users

[selfthinker]

What

The prototype is done in a way that utilises the original file upload input but hides it and adds a new button (and more).
Because the original input is only visually hidden (and from keyboard users) but is not hidden from screen reader users, they will experience two different buttons doing the same thing.

This needs to be investigated how/if the input can be hidden while still using it.

Why

A duplicate button would be confusing to screen reader users.

Who needs to work on this

Frontend developer

Who needs to review this

Accessibility specialist

Done when

• Investigation done into how and if it's possible to have everyone only deal with a single input
• Decision made and logged either how to implement it or what else to do in case it's not possible

[selfthinker]

@owenatgov mentioned in a comment that he fixed it: alphagov/govuk-frontend#5309 (comment)

But the issue is still there. I don't know if maybe it was working but something has changed? Or maybe it was only partially working? (Unfortunately I don't remember anything about that from nearly 3 months ago. But it looks like I was satisfied with it at the time.)