feat(turbopack): Enable `lightningcss` for turbopack by default (#62565)
# Turbopack
* https://github.com/vercel/turbo/pull/7682 <!-- Will Binns-Smith -
Turbopack HMR: url-encode sourceURLs -->
* https://github.com/vercel/turbo/pull/7524 <!-- Donny/강동윤 -
feat(turbopack): Enable lightningcss for turbopack by default -->
### What?
Enable lightningcss by default, for `--turbo` mode.
### Why?
It's time to do it 😄
### How?
Turbopack counterpart: https://github.com/vercel/turbo/pull/7524
Closes PACK-2600