Add size-benchmark for hello-world

[NullVoxPopuli]

Coordinated with (but not dependent on):

• Remove barrel file imports from internal code for better tree-shaking #21350 (see here fer details, goals, and our potential feature (all non-breaking changes!)

This work in this PR will allow us to track our "hello world" size over time.

Note

PR will be red for the package size report, due to main not having the new script

[github-actions]

📊 Package size report — dist/dev   No changes

File	Before (Size / Brotli)	After (Size / Brotli)
Total (Includes all files)	2 MB / 476.3 kB	2 MB / 476.3 kB

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📊 Package size report — dist/prod   No changes

File	Before (Size / Brotli)	After (Size / Brotli)
Total (Includes all files)	1.9 MB / 436 kB	1.9 MB / 436 kB

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Tarball size: 1.2 MB (was 1.2 MB, -50 B)

_{🤖 This report was automatically generated by pkg-size-action}