Fix: Buttons block shows inserter picker when multiple allowed blocks are registered

[adithya-naik]

What

Fixes Buttons block not showing inserter picker when multiple allowed blocks are registered.

Why

The current logic only checks for core/button variations and ignores multiple allowed block types, so it always inserts the default button.

How

Update directInsert logic:

directInsert: !hasButtonVariations && !hasMultipleAllowedBlocks;

Result

• Single block → direct insert (no change)
• Multiple blocks → shows inserter picker

Testing

1. Add a custom button block
2. Allow it inside core/buttons
3. Click ➕ inside Buttons block

Picker should appear.

Issue

Fixes #77839

[github-actions]

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Co-authored-by: Mamaduka <mamaduka@git.wordpress.org>
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[Mamaduka]

Thanks for working on this, @adithya-naik!

I think we can remove the directInsert setting in this case + all useSelect logic. The appender already has all this info and will automatically derive the direct insertion conditions. That's exactly what the inline comment suggested as an improvement, which is now already in place.

P.S. Rebasing on top of the trunk should resolve the failing e2e test.

[Mamaduka]

Okay, it seems there's a minor issue with copying attributes when directInsert isn't specified, but that doesn't change the fix for the Buttons block.

We'll need to fix the attributes to copy the issue first and then land this. @stokesman, I think you were already working on it - #54409. Do you have time to continue work on that PR? I can also take over and handle it.

[adithya-naik]

Thanks for the clarification!

You can take it up and merge it @Mamaduka , and then we can proceed with merging this PR.