Add public interface to create iOS GrGLInterface

GrGLMakeNativeInterface is not compatible with a modular build, so
we need to eventually remove it by giving clients the ability to
explicitly make the interface they need.

This adds such an API for iOS and updates Skia's calls to use that.

Change-Id: Ib81ae09f7c7e47b348382566539f96401766982c
Bug: b/293490566
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/839457
Reviewed-by: Greg Daniel <egdaniel@google.com>
Reviewed-by: Jim Van Verth <jvanverth@google.com>
10 files changed