Accessibility: Creation UI live preview accessibility

[felixfbecker]

Accessibility issues with the live preview:

• The <aside> has no label, meaning it only shows up as "complimentary" in the landmarks list
• When there is no live preview yet, the entire blurred "fake chart" in the background is not hidden from the screen reader and navigated before getting to the text "your live preview will show here"
• The button to refresh the live preview is simply called "Live preview". The refresh functionality is only conveyed visually through the refresh icon.

/cc @Joelkw @felixfbecker @vovakulikov

[vovakulikov]

@felixfbecker Hmm, are you sure that you were looking at the latest main branch? I see that these points were fixed by me a few weeks ago here

I just checked the main and it seems to me that all three points from this issue are in place