Some tests around surface creation and snapshotting with color space

Verify the rules that we're converging on for surfaces:
- For 8888, we only support sRGB-like gamma, or no color space at all.
- For F16, we require a color space, with linear gamma.
- For all other formats, we do not support color spaces.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2270823002

Review-Url: https://codereview.chromium.org/2270823002
diff --git a/bench/nanobench.cpp b/bench/nanobench.cpp
index 4ded061..a2f931e 100644
--- a/bench/nanobench.cpp
+++ b/bench/nanobench.cpp
@@ -471,7 +471,7 @@
         CPU_CONFIG(srgb, kRaster_Backend,
                    kN32_SkColorType,  kPremul_SkAlphaType, srgbColorSpace)
         CPU_CONFIG(f16,  kRaster_Backend,
-                   kRGBA_F16_SkColorType, kPremul_SkAlphaType, srgbColorSpace)
+                   kRGBA_F16_SkColorType, kPremul_SkAlphaType, srgbColorSpace->makeLinearGamma())
     }
 
     #undef CPU_CONFIG