chore(examples): remove with-windicss example (#81846)

## Summary

Delete the entire
[with-windicss](https://github.com/vercel/next.js/tree/canary/examples/with-windicss)
directory and its contents

## Why?

[windicss](https://github.com/windicss/windicss) is
[sunsetting](https://windicss.org/posts/sunsetting.html).

## Adding or Updating Examples

- [x] The "examples guidelines" are followed from our contributing doc
https://github.com/vercel/next.js/blob/canary/contributing/examples/adding-examples.md
- [x] Make sure the linting passes by running `pnpm build && pnpm lint`.
See
https://github.com/vercel/next.js/blob/canary/contributing/repository/linting.md

cc: @samcx

Co-authored-by: Joseph <[email protected]>

Author: JamBalaya56562