dillon1000/react

Remove client caching from cache() API (#27977)

We haven't yet decided how we want `cache` to work on the client. The
lifetime of the cache is more complex than on the server, where it only
has to live as long as a single request.

Since it's more important to ship this on the server, we're removing the
existing behavior from the client for now. On the client (i.e. not a
Server Components environment) `cache` will have not have any caching
behavior. `cache(fn)` will return the function as-is.

We intend to implement client caching in a future major release. In the
meantime, it's only exposed as an API so that Shared Components can use
per-request caching on the server without breaking on the client.