add non-looping option to SkottieViews through xml attributes

stop running animation at the end if not looping


hook looping and background color into SkottieAnimation implementation


add looping attribute to SkottieView

Change-Id: I0c66026429018d61f49ccced1fd5add63619263a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/329816
Commit-Queue: Jorge Betancourt <jmbetancourt@google.com>
Reviewed-by: Derek Sollenberger <djsollen@google.com>
Reviewed-by: Tyler Freeman <fuego@google.com>
4 files changed