efl_input_focus: add event_flags
It appears that it could be interesting to know if a focus event has
already been procecced or not. However, a focus event based on scrolling
activity is not possible, therefore, error about that.
Reviewers: cedric, zmike, stefan_schmidt
Reviewed By: zmike
Maniphest Tasks: T7652
Differential Revision: https://phab.enlightenment.org/D7732