Expose SkSurface::isCompatible

This is part of bridging the explicit backend surface API and making SkSurfaces

This is pulled out of:

https://skia-review.googlesource.com/c/skia/+/222781/ (Add bridge between GrContext::createBackendTexture and SkSurface::MakeFromBackendTexture)

Change-Id: Ib55bcd8a0d1a049f230314a8f8ba7a3951b06d5c
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/223707
Reviewed-by: Greg Daniel <egdaniel@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
6 files changed