Add computation of requestedFeatures to GrProgramInfo and use it

This is a deferred TODO/code review request. In general, this improves the encapsulation of program information w/in GrProgramInfo. Additionally, it is desirable to stop using the Desc/Key to access this information.

Bug: skia:9455
Change-Id: I854ff3225a49657d3a523e88e4bfa549128ee486
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/247336
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
5 files changed