Make GrSamplerState.h and GrRenderTarget.h private

Change-Id: Id7a270f5a528e1a4a6d94474fa092545252753b3
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/234667
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
56 files changed