Splitup GrSimpleMeshDrawOpHelper.h

Change-Id: Ie3d05053633176ba27e55cc2de61eeba1e9f45d6
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/273981
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
13 files changed