efl gfx_path: remove EFL_GFX_PATH_EVENT_CHANGED

efl gfx_path: remove EFL_GFX_PATH_EVENT_CHANGED

Summary:
Here is an additional optmization patch for removing
unnecessary updation of path,

For instance, let's assume this scenario:

If one vg object has 20 path nodes(shapes),
and every single nodes would have 50 path changes.
(like, append_cubic, append_rect, append_xxx ...);
There would 1000 events triggering.

Furthermore, if there are 20 vector objects in one view,
hese events would be triggered 20000 in one frame.

It's insane, actually I could figured out that happens.
and it took a lot of cpu consumption in some vector usages.

efl_gfx_path_commit() is my idea to avoid this.
When path is ready, the path need to get this api call in the last
 to make object changed properly.

@feature

Reviewers: #committers, cedric

Subscribers: segfaultxavi, cedric, #reviewers, #committers

Tags: #efl

Differential Revision: https://phab.enlightenment.org/D7494