cpp/experimental/make exceptional future

@1@ Creates a shared state of type that is immediately ready and stores the exception pointer, then return a future associated with that shared state, as if by. The behavior is undefined if is null.

@2@ Creates a shared state of type that is immediately ready and stores an exception pointer created from, then return a future associated with that shared state, as if by

Return value
A object associated with the shared state that was created.