fix: importmap should insert before module preload link

[fi3ework]

Description

fix #11304.
Vite now moves the existing importmap before the first script. But in #11304, there's a modulepreload link declared after the importmap. After Vite's postImportMapHook, the order became modulepreload importmap script but the correct order should beimportmap modulepreload script, modulepreload should come after import otherwise it will throw an error.

Additional context

The modulepreload link may not indicate the module declared in the importmap. But moving the importmap before all modulepreload link seems like an acceptable and no side effect practice.

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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[bluwy]

Thanks for fixing this! Left a couple comments below. It would be great to add tests for this too in the html playground.

[fi3ework]

Relies on #11515 now to add a test case.