Also: mv experimental/skottie_ios tools/skottie_ios_app
Motivation: make using SkMetalViewBridge that much easier for clients.
Change-Id: I985930ae0751d218e89c48c57b69d85ad7a1e703
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/259279
Reviewed-by: Hal Canary <halcanary@google.com>
Commit-Queue: Hal Canary <halcanary@google.com>
