Android: add support for extracting AnimationDrawable

Required for implementing indeterminate ProgressBar

Task-number: QTBUG-39215
Change-Id: I128eaf2879dd493da86541767a870ea786a5ddf9
Reviewed-by: BogDan Vatra <bogdan@kde.org>
Android: Introduce SimpleJsonWriter

It speeds up the extraction and it reduces memory consumption.

Change-Id: I188f7efbb826343e5bd75f63ace36522f0d7a24d
Reviewed-by: J-P Nurmi <jpnurmi@digia.com>