GH-66090: Self nesting and circular nesting block fix

[SH4LIN]

closes #66090

What?

• This PR checks the current block name when determining if a block is allowed in the inserter. If the parent block name and the current block name are the same, we immediately return false.
• This PR also checks for circular nesting by maintaining a list of blocks that have already been checked. If circular nesting is detected, we return false.
• Additionally, this PR prevents the registration of a block if it is supposed to be added within itself.

Why?

• Self nesting blocks and circular nesting block causes infinite loops.

How?

• This PR checks the current block name when determining if a block is allowed in the inserter. If the parent block name and the current block name are the same, we immediately return false.
• This PR also checks for circular nesting by maintaining a list of blocks that have already been checked. If circular nesting is detected, we return false.
• Additionally, this PR prevents the registration of a block if it is supposed to be added within itself.

Testing Instructions

Testing Instructions for Keyboard

Screenshots or screencast

Fixes/Covers

• Self-nested blocks causing infinite recursion and crashing the editor #66090

[github-actions]

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Co-authored-by: SH4LIN <sh4lin@git.wordpress.org>
Co-authored-by: youknowriad <youknowriad@git.wordpress.org>
Co-authored-by: t-hamano <wildworks@git.wordpress.org>
Co-authored-by: yuliyan <yuliyan@git.wordpress.org>

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[github-actions]

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[youknowriad]

Changes look good to me. Do you think we can add some unit tests?

[t-hamano]

I've confirmed that nested blocks cannot be inserted at the root level, and I've also confirmed the browser warning when registering a block that is itself a parent.

At the very least, we may need to add unit tests for registering blocks here.

[t-hamano]

Suggested change

	if (
	settings?.parent &&
	Array.isArray( settings.parent ) &&
	settings.parent.length === 1 &&
	settings.parent[ 0 ] === name
	) {
	if ( settings?.parent?.[ 0 ] === name && settings.parent.length === 1 ) {

Nit: I don't have a strong opinion, but this might be simpler.

[SH4LIN]

Sure, I'll update the code and add test case

[SH4LIN]

@t-hamano @youknowriad I have updated the code LMK if any further changes are required

[youknowriad]

Thanks for your contribution :)