[Core] Data-plane: enable LRO rehydration

[kinelski]

Our TypeSpec code generator already supports the creation of rehydration tokens to retrieve the status of long-running operations, but the logic to do so has not been wired into our Operation API yet. Once this issue is addressed, the following piece of code is expected to work when rehydrating an operation with return value T:

// Store the rehydration token for later.
RehydrationToken token = operation.GetRehydrationToken().Value;

// Restore the operation with the rehydration token.
Operation<T> operation = Operation.Rehydrate<T>(client.Pipeline, token);