Turbopack: experimental.immutableAssetToken (#88607)
This allows specifying a different deployment id for static immutable assets
- [x] rename `getImmutableAssetToken` to `getAssetToken` (because it can be non-immutable as well)
- [x] disable for webpack
Closes PACK-6534
For https://github.com/nextjs/adapter-vercel/pull/25
Part of PACK-6802
