Build: Reduce VIPS build size by excluding .map and non-minified files

[adamsilverstein]

Summary

• Skip .map source map files in copyDirectory() — sourceMappingURL references are already stripped from JS files by the existing removeSourceMaps transform, so the .map files serve no purpose in Core
• Skip non-minified VIPS JS files — they are ~10MB of inlined WASM binary data with no debugging value over the minified versions
• Always load minified VIPS script modules in wp_default_script_modules(), so SCRIPT_DEBUG mode resolves to the .min.js files that exist on disk
• Saves ~30MB total from the build output

Fixes https://core.trac.wordpress.org/ticket/64734

Test plan

• Run node tools/gutenberg/copy-gutenberg-build.js and verify no .map files are copied
• Verify VIPS directory only contains minified files (worker.min.js, loader.min.js, asset PHP files)
• Verify other script module packages still have their expected files
• Confirm overall build size reduction (~30MB savings)
• Verify VIPS still loads correctly with SCRIPT_DEBUG enabled

Trac ticket: https://core.trac.wordpress.org/ticket/64734

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Props adamsilverstein, swissspidy, westonruter.

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[github-actions]

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[adamsilverstein]

@youknowriad maybe simpler to exclude here for now?

[adamsilverstein]

This worked well in my testing, committing.

[westonruter]

Committed in r61794 (8db1867).

(Not sure why this PR wasn't closed automatically with the commit.)