Tell screen readers when a pop-up opens on the printing page #3

The pop-up screens on the printing page ("Print this?", the first-visit name box and others) are plain divs. Source code/server/public/index.html has no role="dialog" or aria-modal at all, so a screen reader isn't told that a pop-up has opened.

Done when: each pop-up in index.html has role="dialog", aria-modal="true" and an aria-labelledby pointing at its title, and you've tried it with VoiceOver, TalkBack or NVDA. Say in the pull request which one you used.

manage.html can be checked the same way, in this issue or a separate one.