efl_ui: activate widget focus on efl.ui.item.

efl_ui: activate widget focus on efl.ui.item.

Summary:
Unlikely efl.ui.Layout, Item need to be focusable,
so it may traverse list by your command of focus moving.

Test Plan:
tested in
efl_ui_list_example_1.c
efl_ui_grid_example_1.c
check whether item show their focus properly.

scroll feature is not yet supported by efl_ui_scroll itself.

Reviewers: eagleeye, cedric, Hermet, felipealmeida, bu5hm4n

Reviewed By: bu5hm4n

Subscribers: bu5hm4n, cedric, #reviewers, #committers

Tags: #efl

Differential Revision: https://phab.enlightenment.org/D7465