transit: add possibility to revert an ongoing transition during play

transit: add possibility to revert an ongoing transition during play

Summary:
Currently the feature available in transit to reverse play a transition is
auto-reverse which will play a transition in reverse mode once a transition
is complete. This feature helps the user to revert a transition at any point
of time when transition is going on.

New API added.

@feature T3019

Use Case:
While doing pinch zoom, we will be doing zoom transit effect from one step to other, during that transit if user do the pinch in reverse direction this API can be called so that transition will be reverted easily.

Signed-off-by: godly.talias <godly.talias@samsung.com>
Test Plan: elementary_test Transit Resizing / Transit Zoom / Transit Bezier / Transit Custom / Transit Fade / Transit Flip

Reviewers: raster, prince.dubey, shilpasingh, Hermet, seoz, cedric

Subscribers: rajeshps, govi

Differential Revision: https://phab.enlightenment.org/D3567

Signed-off-by: Cedric BAIL <cedric@osg.samsung.com>