eo: make efl_future_then have a data pointer in addition of the object pointer.

eo: make efl_future_then have a data pointer in addition of the object pointer.

Summary:
In the case when you have multiple future in flight related to one object, you
couldn't use the previous version of efl_future_then. Now all function calls
take a void* pointer that allow multiple future to have their private data
request data accessible in all the callback.

This should not break released API as Eo.h is not released yet and so
was efl_future_Eina_FutureXXX_then.

Depends on D7332

Reviewers: felipealmeida, segfaultxavi, vitor.sousa, SanghyeonLee, bu5hm4n

Reviewed By: segfaultxavi

Subscribers: #reviewers, #committers

Tags: #efl

Maniphest Tasks: T7472

Differential Revision: https://phab.enlightenment.org/D7379