Let screen readers announce the block aria label

[IreneStr]

Description

Let screen readers announce the block aria label. The aria label of the blocks used to be on an unfocusable div. We've moved it to the focussable parent div. As a result, the aria-label will be announced by screen readers when tabbing through the blocks.

I've paired on this with enejb

How has this been tested?

• Use a screen reader, for example VoiceOver in combination with Safari.
• Tab through the Gutenblocks of your post.
• The screenreader should announce the block and its type.

Screenshots

'groep' is Dutch for 'group'. It still has to be decided which role is most suitable. That's not part of this fix. (/cc @afercia )

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• My code has proper inline documentation.

[youknowriad]

Approved by @aduth