Genlist: Test case added in Genlist Focus example.
Genlist: Test case added in Genlist Focus example.

Summary:
Added test case to enable/disable mouse wheel. Mouse Wheel is
used to scroll the genlist up/down.

Signed-off-by: Umesh Tanwar <umesh.tanwar@samsung.com>

Test Plan: elementary_test -> Genlist Focus -> Wheel Disabled

Reviewers: raster, Hermet, cedric

Subscribers: sachin.dev, singh.amitesh, SanghyeonLee, eagleeye

Differential Revision: https://phab.enlightenment.org/D2757

rvandegrift/elementary,rvandegrift/elementary,rvandegrift/elementary,FlorentRevest/Elementary,tasn/elementary,tasn/elementary,tasn/elementary,tasn/elementary,tasn/elementary,rvandegrift/elementary,FlorentRevest/Elementary,FlorentRevest/Elementary,FlorentRevest/Elementary