fix: add type: "module" hint to cache directory

[sodatea]

Description

Not sure it's a fix or feat. But adding this hint allows Node.js to correctly load modules inside the node_modules/.vite directory.

Removes the necessity of the following workaround in vite-jest:
https://github.com/sodatea/vite-jest/blob/1e05b4c62df714b1537c76052d5fec761a46c619/packages/vite-jest/vite-server.js#L19-L25

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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• Read the Contributing Guidelines.
• Read the Pull Request Guidelines and follow the Commit Convention.
• Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• Ideally, include relevant tests that fail without this PR but pass with it.

[antfu]

A bit hacky but interesting solution :)

Have you tested with custom cache dir that outside of node_modules? 🤔

[sodatea]

Yeah.
Technically it's not a hack because Node.js has clearly documented how it determines the module type of a .js file:
https://nodejs.org/api/packages.html#packages_type

I also opened #4064 as a more explicit approach.

[patak-dev]

I prefer this approach. Also, seems there are failing tests with the explicit .mjs