Details block: Try double enter to escape inner blocks

[alexstine]

What?

Adds the double enter functionality to exit inner blocks of the details block.

Why?

Improves accessibility for keyboard users.

Fixes: #56263

How?

Adds an __experimentalOnEnter support.

Testing Instructions

1. Open a post or page.
2. Insert a details block.
3. Type a summary.
4. Insert a paragraph block and enter some content.
5. Press enter twice quickly to insert another block (outside of details block) as you can also do with list and quote.

Testing Instructions for Keyboard

Screenshots or screencast

[andrewhayward]

Works as described for me.

Related – and this isn't a new issue, so feel free to ignore – it seems weird to me that you can't ArrowUp into a <details> block. You can ArrowDown through the block, but not back up again; once you get to the block after it, ArrowUp is ignored and movement just stops.

Instead you have to Escape into navigation/selection mode, then move around.

[github-actions]

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Co-authored-by: alexstine <[email protected]>
Co-authored-by: andrewhayward <[email protected]>
Co-authored-by: carolinan <[email protected]>
Co-authored-by: talksina <[email protected]>

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