ecore-evas/buffer: implement ignore_events method

ecore-evas/buffer: implement ignore_events method

Summary:
this is a simple implementation of ignore_events functionality which
sets pass_events if it's an image or prevents the emission of events
in other cases

the result should be that no user events are received. this deliberately
does not block the triggering of resize callbacks as in the original ticket
since this guarantees broken functionality and is just not a good idea

fix T4700

Reviewers: devilhorns, Hermet

Reviewed By: Hermet

Subscribers: Hermet, cedric, #reviewers, #committers

Tags: #efl_display_system

Maniphest Tasks: T4700

Differential Revision: https://phab.enlightenment.org/D6876