[graphite] Add Device::readSurfaceView

Both SkImages and SkSpecialImages are often created by pulling the read view out of a Device.

Bug: b/241427862
Change-Id: I72bee547b265ecd6b03031eea7e7c1dcd359523f
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/573645
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
4 files changed