Change GrGpu::onCreateCompressedTexture signature

In the previous form there was some duplication between the backend format and the SkImage::CompressionType being passed around.

Bug: skia:9680
Change-Id: I04455b7a4289bec83d87be17b75b4e9d4d6ef2e0
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/261184
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
26 files changed