Summary:
this new API can be used to get a easy to use iterator, to iterate
through all the children of a specific widget.
ref T7553
Reviewers: stefan_schmidt, zmike, cedric, segfaultxavi
Reviewed By: segfaultxavi
Subscribers: woohyun, cedric, #reviewers, #committers
Tags: #efl
Maniphest Tasks: T7553
Differential Revision: https://phab.enlightenment.org/D8014
