Remove GrProgramDesc's need for the GrGpu

Although not strictly necessary, being able to compute the program key w/o needing access to the Gpu will give us more flexibility.

Bug: skia:9455
Change-Id: I0cd76d79a3008b69be18636be370e7aaa531bc65
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/247686
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
22 files changed