Error message should use paragraphs rather than spans

[edwardhorsford]

Bug Report

Our error message component uses spans, where I think it should use paragraphs. I checked GOV.UK and it used to use spans prior to v4.0 - it was changed in this pr.

I suspect one consequence of this is that VoiceOver will read the error message in a less clear way.

With the gov.uk design system, VoiceOver reads the error message as one line: Error: The date your passport was issued must be in the past. With ours, it reads Error: on its own, and you have to manually advance to the next bit. I suspect this is because VoiceOver treats spans within a block level element as one thing, but when it's inline elements in inline elements it treats them separately.