#a11y-headings - the Updates screen

[afercia]

In the Updates screen, while the update process is running, some headings appear, one for each updated item:

These headings are currently <h4> so there are two missing levels, however they're inside an iframe which, technically, is a separated document.
Wondering what to do here, would changing them in <h2> be correct?

#a11y-headings

[afercia]

The attached patch changes these headings in <h2>, waiting for some feedback tough.

[afercia]

Refreshed patch to take care of the headings also when updating translations (or core):

[afercia]

We've discussed a bit this ticket in our last accessibility team chat on Slack, for a more proper semantic all the updated items should be probably marked up as list items. After all this is a list, even when there's just one update.
By the way there are many things running here: PHP output buffering, error handling, inline JavaScript, etc. I'd be inclined to keep it simple and just change the headings level.

[afercia]

In 35219:

Bump H4 headings to H2 in the Updates screen for better accessibility.

Fixes #34265.