next.js

cfcfabab - [Turbopack] add unstable prefix to persistent caching option and force to provide an expected level of stability (#71090)

[Turbopack] add unstable prefix to persistent caching option and force to provide an expected level of stability (#71090) ### What? Rename option to `unstablePersistentCaching` and require to pass a persistent caching version (currently 1). We increase the number when making improvements to persistent caching. Smaller numbers are accepted too, but providing a larger number will fail the build. e. g. if we document `experimental.turbo.unstablePersistentCaching: 5`, this will only work for next version that ship at least persistent caching with version 5. Older version would be rejected.