Plumb GrBackendFormat into the GrPrimitiveProcessor::TextureSampler

This is not a substantive CL. It is just setting up for removing the
usage of the GrGpu in the creation of the GrProgramDesc.

Change-Id: Ic24204de256862e5e780626bde3a44f4d735c6e9
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/249121
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
12 files changed