Block editor: 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]

The following accounts have interacted with this PR and/or linked issues. I will continue to update these lists as activity occurs. You can also manually ask me to refresh this list by adding the props-bot label.

If you're merging code through a pull request on GitHub, copy and paste the following into the bottom of the merge commit message.

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>

To understand the WordPress project's expectations around crediting contributors, please review the Contributor Attribution page in the Core Handbook.

[github-actions]

👋 Thanks for your first Pull Request and for helping build the future of Gutenberg and WordPress, @SH4LIN! In case you missed it, we'd love to have you join us in our Slack community.

If you want to learn more about WordPress development in general, check out the Core Handbook full of helpful information.

[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 :)