Add ColorCodecSrc for testing/comparison on color corrected decodes

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1933753002

Review-Url: https://codereview.chromium.org/1933753002
diff --git a/bench/nanobench.cpp b/bench/nanobench.cpp
index 5e26b48..7999ad5 100644
--- a/bench/nanobench.cpp
+++ b/bench/nanobench.cpp
@@ -606,7 +606,7 @@
         fUseMPDs.push_back() = false;
 
         // Prepare the images for decoding
-        if (!CollectImages(&fImages)) {
+        if (!CollectImages(FLAGS_images, &fImages)) {
             exit(1);
         }