Fix 2 animatedImageVisual issues

 - 1. Make animate image visual do not caching in texture-manager
  - If 2 visual those have same image url and play without sync, it makes caching error.
 - 2. Make NextFrame methods.
  - Currently, the visual requests to load specific frame with index.
    But, if the system getting slow(like so many agif/webp in playing), the request and the loading can not be synchronized.
  - The visual will request next frame index with identical timing, but because the loading is slow, the loading frame will be throwed away and start next frame of the index.
  - This make bottle neck and also make stop to play.
  - This patch adds NextFrame that returns prepared next frame. If the next frame is in loading, this method is not to increase index and returns current rendered frame again.

Change-Id: Ia301ae654bcf8ee88167585bc4f4b1259a1e4e46
Signed-off-by: Seungho Baek <sbsh.baek@samsung.com>