fix(import-analysis): preserve importedUrls import order

[bluwy]

Description

Fix withastro/astro#8044

In import analysis, we're transforming the imports populate importedUrls in parallel, causing it to be non-deterministic. This affects frameworks that crawl the module graph for CSS to populate the HTML to prevent FOUC, e.g. SvelteKit and Astro (afaia), causing the CSS order to be incorrect.

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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[Dunqing]

I've looked into this before. I thought it was intentional.

[bluwy]

It was deterministic before #12754 so very likely unintentional here 😬 Though there is a point that Set shouldn't exactly be ordered, but I think it makes sense to ensure that as there's a usecase for it.