SkSurfaceProps now has a gamma-correct ("AllowSRGBInputs") flag. That's propagated in a few places so that the backend can do the right thing for L32 vs S32 mode.

Also added SkSurfaceProps to SkSpecialImage, so that Image -> Surface conversion can preserve the desired behavior during filtering.

Many small changes, including a bunch of comments about places where we may be losing information right now. My approach was to ensure that if anything fails, it will always fall back to "legacy" mode - gamma-correctness is opt-in, so I'll just have to feed things through as missing cases are exposed.
BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1838953007

Review URL: https://codereview.chromium.org/1845283003
diff --git a/src/gpu/GrPaint.cpp b/src/gpu/GrPaint.cpp
index af93e8f..f41469e 100644
--- a/src/gpu/GrPaint.cpp
+++ b/src/gpu/GrPaint.cpp
@@ -15,6 +15,7 @@
 GrPaint::GrPaint()
     : fAntiAlias(false)
     , fDisableOutputConversionToSRGB(false)
+    , fAllowSRGBInputs(false)
     , fColor(GrColor_WHITE) {}
 
 void GrPaint::setCoverageSetOpXPFactory(SkRegion::Op regionOp, bool invertCoverage) {