Reland "Move GPU specific ImageFilter context factories to src/gpu/"

This is a reland of commit 484fbc1e9c5ee81040f239769294b2b0740b26ae

Original change's description:
> Move GPU specific ImageFilter context factories to src/gpu/
>
> This removes ganesh- and graphite- specific code out of
> src/core/SkImageFilterTypes
>
> Bug: skia:14317
> Change-Id: I6c4a62ede656c97e83663dc8c7cffa1803005eea
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/717976
> Commit-Queue: Kevin Lubick <kjlubick@google.com>
> Reviewed-by: Michael Ludwig <michaelludwig@google.com>

Bug: skia:14317
Change-Id: Ie82050c789bf21a7892dc992b189a5b9f4dbb0e4
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/718976
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
12 files changed