Set a callback to be called when the future resolves
It is not allowed to call the following functions from the callback as they could either creash the application or lead to the callback thread being blocked.
NABTO_CLIENT_DECL_PREFIX NabtoClientError NABTO_CLIENT_API nabto_client_future_set_callback2(NabtoClientFuture* future, NabtoClientFutureCallback callback, void* data)
- [in] The future.
- [in] The callback.
- [in] User data for the callback.
NABTO_CLIENT_EC_OK iff the callback is set