[NUI] Support EncodedImageBuffer ImageType property + Upgrade EncodedImageBuffer...

[NUI] Support EncodedImageBuffer ImageType property + Upgrade EncodedImageBuffer demo

Let we allow to give the type of buffer s.t. what buffer is mean.
We can load svg and lottie image as encoded image buffer now.

+

Let we make EncodedImageBuffer can be created at worker thread.
And make the demo to load buffer asynchronously.

This patch have dependency with below dali patch :

https://review.tizen.org/gerrit/c/platform/core/uifw/dali-csharp-binder/+/301314

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