Migrate BuiltinTypes to a separate file from Context.

No code or functionality changes.

Change-Id: I24317767570ae9ebbfea56f873d98709fb22d8b9
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/354876
Commit-Queue: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
5 files changed