efl_ui_spec: add test suite for range_display events

Summary:
this test case ensures the correct emittation of the newly added events.

ref T7895
Depends on D9372

Reviewers: segfaultxavi, zmike, woohyun, cedric

Reviewed By: cedric

Subscribers: cedric, reviewers, committers

Tags: efl

Maniphest Tasks: T7895

Differential Revision: https://phab.enlightenment.org/D9373