Support `Uint8Array` bodies when generating cache keys for POST requests (#81465)
When opting into caching a POST request with the `revalidate` option, or
when the Server Components HMR Cache implicitly caches a POST request,
the body of the request is now correctly handled if it is a
`Uint8Array`. Previously, we logged `Failed to generate cache key for
...` and the cache was bypassed.
closes NAR-180