Support animated stickers on Android (#737)

* support animated stickers on Android

* [Android] Add WHO pack as animated pack

* [Android] add animated pack indicator in sticker pack list

* [Android] set sticker animation indicator on details view

* [Android] add tap to preview

* [Android] add animated sticker file validation

* [Android] Add existing file dimension and size when showing error

* [Android]improve format of error message.


Co-authored-by: Simon Xu <simonxuzhe@fb.com>