feat: add importedCss and importedAssets properties to RenderedChunk type

[aleclarson]

Description

Replace the internal chunkToEmittedCssFileMap and chunkToEmittedAssetsMap variables with public properties added by Vite to RenderedChunk objects in the renderChunk phase.

These can be useful for Vite-based frameworks that generate their own HTML. We also want to move toward decoupling the internal HTML/CSS/Asset plugins, and this feature helps with that.

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

[bluwy]

Looks like a clean refactor to me.

[patak-dev]

Queued for discussion in the next team meeting 👍🏼

[patak-dev]

@aleclarson we talked about the PR in yesterday's meeting and we are good to move forward. The only change to merge is to nest importedAssets and importedCss in chunk.viteMetadata, so we can later continue to expand the metadata without possible collisions with rollup (or other bundlers like WMR).

We also considered using an internal WeakMap and exposing a getViteChunkMetadata(chunk) function instead but it looks less ergonomic to use.

[ElMassimo]

I can make the suggested changes if needed (if you would prefer @aleclarson).

[aleclarson]

@ElMassimo No need to ask, go right ahead ;)

[ElMassimo]

@patak-dev @aleclarson Applied the suggested changes in a pull request targeting this branch.

Please review, and if it looks good we can go ahead and merge that one first.

[patak-dev]

Looks good! Thanks @ElMassimo for doing the changes. Lets check if we can start the 2.9 beta next week and merge this one then.