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/dm/DM.cpp b/dm/DM.cpp
index fe1432b..9dbd43a 100644
--- a/dm/DM.cpp
+++ b/dm/DM.cpp
@@ -779,7 +779,7 @@
     }
 
     SkTArray<SkString> images;
-    if (!CollectImages(&images)) {
+    if (!CollectImages(FLAGS_images, &images)) {
         return false;
     }
 
@@ -795,6 +795,16 @@
         }
     }
 
+    SkTArray<SkString> colorImages;
+    if (!CollectImages(FLAGS_colorImages, &colorImages)) {
+        return false;
+    }
+
+    for (auto colorImage : colorImages) {
+        ColorCodecSrc* src = new ColorCodecSrc(colorImage, ColorCodecSrc::kBaseline_Mode);
+        push_src("image", "color_codec_baseline", src);
+    }
+
     return true;
 }