Make Program owned-elements public.

Change-Id: I7680376d0f0a7bbaa7cb845e2223b9ce4d29c96f
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/456797
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
5 files changed