feat!: add support for tailwindcss v4

[Jaush-M]

No description provided.

[colinaaa]

The plugin aims to:

1. Seamlessly integrate Tailwind CSS into Rsbuild without requiring any configuration.
   • Eliminates the need for content in Tailwind v3 or @source in Tailwind v4.
2. Automatically generate CSS for each entry point based on its specific usage.

Your implementation appears to base on PostCSS, which deviates from the intended purpose of this plugin.

You can see more information at #17 (comment)

Before completing the implementation of Tailwind CSS V4, you can start using the PostCSS plugin by following the guide.