The UrlInput component is not accessible

[afercia]

The UrlInput component added in 4dc462c to support optional links in image blocks, is made of two buttons and one input field:

The two buttons are "empty": there's no text or aria-label that assistive technologies can announce. Screen reader will read out just "button".

A very basic requirement for web standards and accessibility is that all user interface controls need to be labeled.

In this case, an aria-label with a meaningful text would be ok.

The input field misses a properly associated label. All input fields need to be associated with a label, that can be visually hidden. Alternatively, they can use an aria-label attribute. Placeholders are not a replacement for labels.

[afercia]

Fixed in #1856