Replace GrColor4h with SkPMColor4f

- Mechanical replacement of GrColor4h (used throughout Ops) with
  SkPMColor4f.
- API adaptation (to/FromGrColor -> to/From_BytesRGBA).
- Complete removal of FromFloats (source was already SkPMColor4f),
  and toFloats (setting uniforms can directly access .vec()).

Bug: skia:
Change-Id: I37eece1fa7ed2545dc6843e840d4cc3c60f19747
Reviewed-on: https://skia-review.googlesource.com/c/166620
Reviewed-by: Mike Klein <mtklein@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
diff --git a/tests/ProcessorTest.cpp b/tests/ProcessorTest.cpp
index ff6fa33..d0da21f 100644
--- a/tests/ProcessorTest.cpp
+++ b/tests/ProcessorTest.cpp
@@ -46,7 +46,7 @@
 
     RequiresDstTexture finalize(const GrCaps& caps, const GrAppliedClip* clip) override {
         static constexpr GrProcessorAnalysisColor kUnknownColor;
-        GrColor4h overrideColor;
+        SkPMColor4f overrideColor;
         fProcessors.finalize(kUnknownColor, GrProcessorAnalysisCoverage::kNone, clip, false, caps,
                              &overrideColor);
         return RequiresDstTexture::kNo;