Add a renderer key to lottie gold digests

This will help us distinguish between "rendered by skottie",
"rendered by lottie-web", etc.

Bug: skia:8108
Change-Id: I48b489adf8f8b7f950df397e5e94c1103dc4d306
Reviewed-on: https://skia-review.googlesource.com/149237
Reviewed-by: Stephan Altmueller <stephana@google.com>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
3 files changed