fix(metadata): expose viteMetadata type

[bluwy]

Description

fix #11324

I believe viteMetadata is public API (we also export the ChunkMetadata types), but when a user creates a Vite plugin with renderChunk(), the chunk autocomplete doesn't show viteMetadata as a possible property.

This is because the declare module augmented types isn't bundled by api-extractor. This PR re-shuffles the types so that the augmented types are in types/metadata.d.ts, and node/index.d.ts would re-export the ChunkMetadata types from it. Indirectly doing so, the augmented types are detected by TypeScript too.

Additional context

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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