list: focus highlight is handled by item theme.

list: focus highlight is handled by item theme.

Summary:
Problem: list theme (elm/list/base/default) is an alias of scroller
base theme (elm/scroller/base/default) in which focus_highlight is set to "on".
Solution: Now focus highlight in_theme is set by list item theme.

Test Plan: elementary_test->"List Focus"

Reviewers: seoz, woohyun

Reviewed By: seoz

CC: nirajkr
Differential Revision: https://phab.enlightenment.org/D572