feat: support .astro files

[drwpow]

Description

Adds ability for Vite to scan .astro files for dependencies. Doesn’t affect default behavior of scanning (.astro files aren’t scanned by default). Requires optimizeDeps: { entries: '**/*.astro' } to opt in.

Additional context

Should I add a playground example? Should I add playground + tests?

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

Before submitting the PR, please make sure you do the following

• 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.

[patak-dev]

This looks good @drwpow, we don't need tests or to add a playground for this particular change 👍🏼

[patak-dev]

I'll merge this one as it was already discussed with the team.