Enforce Block Restrictions Across All Nesting Levels

[TechSubham]

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Resolved an issue where block restrictions were only applied to top-level blocks, ensuring proper enforcement across all nested levels to prevent duplicates.

Closes #2837

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[stevepiercy]

@TechSubham please update this PR title ("issue fixed" is not good) and provide a sufficient description so someone can see at a glance what this PR is for. Thank you!

[stevepiercy]

This requires a technical review from @plone/volto-team.

[stevepiercy]

News LGTM. Thanks for renaming the PR. We await a tech review. Thank you for your work and patience!

[TechSubham]

@stevepiercy Thanks

[stevepiercy]

@TechSubham also can you update your branch against main and push? Do you see the Update branch button, and can you click it?

[sneridagh]

@TechSubham I think that #2837 issue was not about this... Also it is highly unlikely that the title block appear in a nested context.

Also, that logic applies only to the title block, eg. when there is a title block already in the page, do not allow add another one. So, as you can see the scenario is quite limited.

#2837 wanted to convey another idea/deficiency, not about the specific use case about the title.

@tiberiuichim any feedback about the original issue?