Revert "evas: make efl_canvas_animation abstract"

Efl.Canvas.Animation class can be used for custom animation with
Efl.Player class' event callbacks as follows.

Example code:

void _anim_running_cb(void *data, const Efl_Event *event)
{
   //Do custom animation
}
{
   Eo *anim = efl_add(EFL_CANVAS_ANIMATION_CLASS, win);
   Eo *player = efl_add(EFL_CANVAS_ANIMATION_PLAYER_CLASS,
                        efl_animation_player_animation_set(efl_added,
                                                           anim));
   efl_event_callback_add(player, EFL_ANIMATION_PLAYER_EVENT_RUNNING,
                          _anim_running_cb, NULL);
}

As a result, Efl.Canvas.Animation is required to be a regular class
instead of an abstract class.

This reverts commit ea9ff9f547.

src/lib/evas/canvas/efl_canvas_animation.eo

@@ -1,6 +1,6 @@
 import efl_canvas_animation_types;
 
-abstract Efl.Canvas.Animation extends Efl.Object implements Efl.Playable
+class Efl.Canvas.Animation extends Efl.Object implements Efl.Playable
 {
    [[Efl animation class]]
    eo_prefix: efl_animation;