Implement some cases for ExternalTexture usage

Implement some cases for ExternalTexture usage

 - Support external texture as input of masking
 - Make already cached masking input for external texture works well
 - Make fail to load masking input for external texture works well
 - Ignore RELOAD action for external texture
 - Allow to support AnimatedImageVisual with ExternalTexture and Buffer
 - Load with external texture create another texture id
 - (Extra) Cache masking image and for AnimatedImageVisual case
 - (Extra) Move external resource reference control codes to VisualUrl

Furthermore, let we make good utility to convert from location to
TextureId at VisualUrl.

TODO : Some UTC crashed after cache sync loaded AnimatedImageVisual result.
We should fix it soon.

Change-Id: I7f45255a33af280b2e57e589fda7b294eb660465
Signed-off-by: Eunki, Hong <eunkiki.hong@samsung.com>