Rename lots of things from 'sRGB' to 'GammaCorrect', where appropriate

Trying to be much more explicit about where we really mean sRGB as a format,
and where we mean gamma-correct, as in: "not legacy behavior". Most of the
changes to rendering behavior are dependent on the latter, so let's be precise.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1884873006

Review URL: https://codereview.chromium.org/1884873006
diff --git a/tools/gpu/GrTest.cpp b/tools/gpu/GrTest.cpp
index 95b7802..c707b69 100644
--- a/tools/gpu/GrTest.cpp
+++ b/tools/gpu/GrTest.cpp
@@ -156,7 +156,7 @@
     SkMatrix mat;
     mat.reset();
     if (!SkPaintToGrPaint(this->context(), paint, mat,
-                          this->surfaceProps().allowSRGBInputs(), &grPaint)) {
+                          this->surfaceProps().isGammaCorrect(), &grPaint)) {
         return;
     }
     SkMatrix textureMat;