Make h2 setup vite command stable

[frandiox]

WHY are these changes introduced?

The h2 setup vite command was experimental and it had a few issues. This PR makes it more robust and removes the "experimental" confirmation prompt.

WHAT is this pull request doing?

It now covers most of the steps in the Remix upgrade guide: https://remix.run/docs/en/main/future/vite

• Throw if project is already using Vite
• Remove deprecated Remix css-bundle dependency
• Support CSS Modules
• Support Vanilla Extract
• Improve edge cases for Tailwind support
• Move some remix.config.js properties to vite.config.js (appDirectory, routes, ignoredRouteFiles, future)
• Notify about MDX support to set it up manually if it was used

HOW to test your changes?

h2 setup vite in project variations with vanilla-extract, modules, changes in remix.config.js etc.

[shopify]

Oxygen deployed a preview of your fd-improve-setup-vite branch. Details:

Storefront	Status	Preview link	Deployment details	Last update (UTC)
vite	✅ Successful (Logs)	Preview deployment	Inspect deployment	March 28, 202411:55 AM
third-party-queries-caching	✅ Successful (Logs)	Preview deployment	Inspect deployment	March 28, 202411:55 AM
custom-cart-method	✅ Successful (Logs)	Preview deployment	Inspect deployment	March 28, 202411:55 AM
subscriptions	✅ Successful (Logs)	Preview deployment	Inspect deployment	March 28, 202411:55 AM
optimistic-cart-ui	✅ Successful (Logs)	Preview deployment	Inspect deployment	March 28, 202411:55 AM
skeleton	✅ Successful (Logs)	Preview deployment	Inspect deployment	March 28, 202411:55 AM

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