Closes #44904

Adds the Tailwind CSS LSP as suggested here:
https://github.com/zed-industries/zed/pull/39517#issuecomment-3368206678.
This allows users to use the Tailwind CSS LSP for CSS files, to support
Tailwind specific rules.

Docs will be added in a separate PR after this is released

Release Notes:

- Add Tailwind CSS Mode support, for Tailwind specific CSS rules like
`@apply`, `@layer`, and `@theme`.