Change UrlBehavior.static_suffix to ResolvedVc<Option<RcStr>> (#89921)
## Summary
Changes `UrlBehavior.static_suffix` from `Option<RcStr>` to `ResolvedVc<Option<RcStr>>` so that `css_url_suffix` stays as a Vc longer instead of being eagerly resolved at the call site. This improves caching behavior by keeping the value cell-based through the chunking context construction.
- Updated `UrlBehavior` struct definition in `turbopack-core`
- Updated default fallbacks in browser/nodejs chunking contexts
- Updated CSS url reference consumer to `.await?` the `ResolvedVc`
- Replaced `.owned().await?` with `.to_resolved().await?` in next-core callers