Buttons Block: Show inserter if button have variations (#53498)

[petitphp]

What?

This PR update the Buttons block to show the inserter if the button have variations. Fix #53498

Why?

Currently, when adding a button's variation with the default scope, there is no way to use that variation due to the directInsert option in the innerBlocksProps which bypass the inserter. The only way is to add the transform scope.

How?

This PR change the value of the directInsert option if button variations exists.

Testing Instructions

Snippet to register a button variation :

wp.blocks.registerBlockVariation('core/button', {
	name: 'custom-button',
	title: 'My custom button',
	scope: ['transform', 'inserter', 'block'],
	attributes: {className: 'my-custom-button'},
});

Instructions

1. Edit a post,
2. Add a Buttons block,
3. Add a button, the button should be added directly without showing the inserter,
4. Using the browser console, register a button variation,
5. Add a button, the inserter should appear and let you select between the default button and the variation.

Screenshots or screencast

[stokesman]

Thanks for the PR! I tested it out and found the direct insert works as before when no variations are registered and when variations are registered the menu is available. The code looks fine to me as well. It might be a smidge better if instead of adding another useSelect the existing one were reused. You could change that if you'd like or otherwise I'll get to it in #53786 (I'll keep that drafted in deference to getting this PR dealt with first).

Google.Chrome.-.Edit.Post.My.WordPress.Website.WordPress.2023-08-17.at.3.10.46.PM.mp4

[Mamaduka]

A more general solution would be to solve this in the Inserter component, so every block using the exact option doesn't have to handle it separately.

I think shipping this solution is okay, but let's include a comment that we want Inserter to handle this logic eventually.

P.S. Meanwhile, the Inserter component could use some refactoring 😄

[petitphp]

@stokesman Thanks for the review. I've applied your suggestion and merge the new useSelect with the existing one.

@Mamaduka I've added a comment. I don't know enough Gutenberg to see what should be refactored in the Inserter but happy to help work on it !

[Mamaduka]

Thanks for the follow-up, @petitphp!

I've Inserter on my todo list, and I hope I'll find time before WP 6.4.

P.S. Failing test isn't related to this PR, but we'll have to wait until the project's flaky Playwright test is resolved.

[stokesman]

Thanks for rebasing @petitphp. I'll go ahead a pull the trigger here since all tests are passing.

[youknowriad]

Was this considered a follow-up? What prevented us from actually implementing this solution?

[stokesman]

I understood it to be for a follow-up.

What prevented us from actually implementing this solution?

I suppose nothing besides someone putting in the effort. I've taken a closer look and the logic is actually already there. It seems the Buttons block was working as in this PR before #37905. In that PR directInsert: true was added and which forces it even when there are variations. I think I found a way to reconcile this.