feat: unplugin-preprocessor-directives

[KeJunMao]

Clear and concise description of the problem

I developed https://github.com/KeJunMao/vite-plugin-conditional-compile/ to use conditional compilation in vite, and as of now it has only 35 stars and 1000+ npm downloads, but is used as a direct dependency by https://github.com/web-scrobbler/web-scrobbler and https://github.com/ZhUyU1997/open-pose-editor

On August 30th I saw that the unplugin organization was formed and I rewrote it to https://github.com/kejunmao/unplugin-preprocessor-directives

Sorry, I ignored the Package Contribution requirements :(

If I ever get the chance, I'd be honored to join unplugin!

Suggested solution

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No response

Additional context

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Validations

• Follow our Code of Conduct
• Read the Contributing Guide.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.

[sxzz]

LGTM, WDYT @antfu

[antfu]

The project seems to be quite new, I'd wait a bit for more adoptions.