Add roots/wordpress for WordPress code symbol discovery by IDEs/editors

[thelovekesh]

Summary

When working with wp-env, code editors and IDEs often struggle to locate WordPress code symbols. This PR introduces roots/wordpress, which dumps core files into the vendor/roots/wordpress directory. This enhancement improves developer experience (DX) by enabling IDEs and editors to resolve function and class symbols more effectively.

Relevant technical choices

• Add roots/wordpress package.
• Add config to add WordPress files in vendor/roots/wordpress.

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Co-authored-by: thelovekesh <thelovekesh@git.wordpress.org>
Co-authored-by: westonruter <westonruter@git.wordpress.org>
Co-authored-by: swissspidy <swissspidy@git.wordpress.org>

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[westonruter]

Humm. We already have core files locally, however, when wp-env had started. Personally I symlink vendor/wp-env/wp-core to the path returned by wp-env install-path. This gets me the the symbols as well as when I jump to a definition for some symbol in core, I can actually modify the core source code and it is the actual code that is being used in the running environment. If we added the core files to vendor/roots/wordpress then there would be another copy that isn't doing anything.

[swissspidy]

We also already have the WordPress stubs from PHPStan. If we added this then there would be another copy that isn't doing anything.

[westonruter]

Maybe later