Create Block: Unify WordPress packages installation

[Adi-ty]

What?

Unifies the installation of @wordpress/scripts and @wordpress/env packages by adding them directly to devDependencies, then running a single npm install command.
Follow-up to #71072

Why?

As suggested by @gziolo , running multiple separate npm install commands is inefficient. The current approach runs:

1. npm install (for custom dependencies)
2. npm install @wordpress/scripts --save-dev (in init-wp-scripts.js)
3. npm install @wordpress/env --save-dev (in init-wp-env.js)

This creates unnecessary network overhead and slower scaffolding experience.

How?

• Modified package.json creation to include WordPress packages in devDependencies when requested
• Updated init-wp-scripts.js and init-wp-env.js to remove npm install

[github-actions]

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Co-authored-by: Adi-ty <iamadisingh@git.wordpress.org>
Co-authored-by: gziolo <gziolo@git.wordpress.org>

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[gziolo]

Thank you for the follow-up. I left some feedback to consider.

[Adi-ty]

Thank you for the follow-up. I left some feedback to consider.

Hi @gziolo, apologies for the delay in implementing the feedback on this PR. I’ve now addressed the suggested changes based on your review. Thanks again for the feedback.