Update fetch cache handling with POST requests (#46856)
This updates to no longer skip caching POST or authed requests with the
fetch cache and instead we bail when `cookies()` or `headers()` is used
prior which is a better heuristic to signal user specific data would be
related to the fetch request.
x-ref: [slack
thread](https://vercel.slack.com/archives/C042LHPJ1NX/p1678130069138849)
## Bug
- [x] Related issues linked using `fixes #number`
- [x] Integration tests added
- [ ] Errors have a helpful link attached, see
[`contributing.md`](https://github.com/vercel/next.js/blob/canary/contributing.md)
