Reduce GrCaps' reliance on GrPixelConfig

By itself this CL isn't all that compelling but I believe we need some intermediate path to wean ourselves off of GrPixelConfig. In particular, I believe isFormatTexturable will not need an SkColorType parameter in the future.

This is pulled out of:

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

which adds SkSurface::isCompatible - so the SkSurface_Gpu::isCompatible calls have been removed from this CL.

Change-Id: I6c2b8a2c4af98c1437b92c58513f34014e551b2e
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/223188
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
16 files changed