Add launch screen to iOS apps

Bug: skia:
Change-Id: I7ebe94213c26c31c1b0dbd1b8951f87263cd41a3
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/175826
Commit-Queue: Jim Van Verth <jvanverth@google.com>
Reviewed-by: Hal Canary <halcanary@google.com>
6 files changed